If so, what is your rationale, and what has your experience been?

I have some limited indirect exposure. But I do not hold any gold / precious metals funds or stocks at this time..
My experience: Gold / PC miners are explosive (no pun intended). There is a string of 5 consecutive years (2011-2015) where most gold / precious metals mining funds lost money every year, losing about 90% of value over those 5 years. Breathtaking. But gold is prone to sharp “up” years as well. A mining fund can gain 50% + in a good year.
Performance / Yahoo / Click the “show more” tab to pull up longer term performance for both OPGSX and the broader fund category.
I won’t touch the miners at my age. They are more volatile than the metal. (Albeit - those in the know say the miners are currently undervalued relative to the metal.) Like @Derf I own PRPFX. One of my CEFs has a bit of exposure to the miners. When I feel like gambling I buy a little GLTR. It combines gold bullion with some silver and platinum using derivatives. Don’t feel like gambling right now. Prices look rich to me.
Rationale for owning / not owning? When rising sharply gold is cited as a hedge against inflation and a “safe haven” during times of war or social upheaval. Also as a way of diversifying. When falling, critics say it hasn’t done nearly as well as equities longer term, does’t generate any income, can be difficult to trade (very narrow market) and is expensive to store.

We haven't held any gold/metals related since 1979 - early 1980's. The below charts are gold miners, gold and SPY for a reference.
GDX vs GLD vs SPY chart 2006 to present
Chart August 2008 - August 2010, 2 years during 2008 market melt
Chart COVID period, January 2020 - January 2022
Chart Ukraine invasion, January, 2022 - July, 2024
Chart YTD
NOTE: a fellow I worked with for 30 years was/is a guns and gold kinda person.
He became so freaked out with the market melt in 2008, that he cashed out a portion of his T-IRA to purchase physical gold at a local coin dealer store. That wasn't a good plan.

Observations:
1) Gold has been a terrible investment for a long term holders.
2) If you are a good trader, why bother with gold.
3) Investing small % is meaningless longer term.
4) The breakdown of the world is a long term scare that hasn't materialized.

Studies have indicated exploiting the momentum factor can generate alpha.
Skilled traders who use momentum may be able to harvest some of this alpha.
Numerous studies also indicate active trading often leads to poor performance.
I contend the vast majority of individual investors should create a sensible investment
plan and then strive to minimize trading activity.

I agree with the above and what I have been posting for many years.
On the other hand, I also posted that most investors should use up to 5-7 funds and rarely trade.
What I have seen on several sites for over 15 years is the worst of both. Too many funds and too many trades without any consistency, and many times trading at the worst time.
Remember, create a system, test and retest, make changes until it is worth it, and stick to it. Trading is like swimming; practice makes you better, but trading randomly doesn't make sense.
Hint: valuation and low fund expense ratio should not lead your trading and why there are investors who have been holding Value and EM in the last 15 years.

Some explanations for the chart:
There is 50-yr worth of data color coded for 5 decades.
The solid line is the best-fit line. So, it says, for example, that if the initial yield was 5% (read on the horizontal axis), the approximate TR in 5-year forwards could be expected to be 5.2% (read on the vertical axis); the range of TR was 4.2-6.0% and the period was 2000s.
But there is scatter around the solid line with large scatterings (notable undershots) in 1970s (an era of very high yields) and 2010s (an era of very low yields). But much of the scattering is in a narrow band.
R^2 of 88% or 0.88 means r of 0.94. So, this linear regression should be considered good for these data points.
Possible criticisms:
1. The US Agg Bond Index has had variable duration that were different from the 5-year forward period used for the study.
2. Such linear regressions may work better for intermediate-term Treasuries, but the US Agg Bond Index is less than half in government bonds (Treasuries, Agencies) with the rest in corporate and securitized bonds.

+1.

Ah, yes; I should have used Schwab. ER of .035% = almost free !
SWLGX M* performance
We're only talking 10% of an entire portfolio.

@crash
i worked at the VA for 8 years. The most frustrating experience in my life, based on quality of care. But I got paid. In private practice I would gladly have taken care of veterans ( and Title 19) if they had a system set up to pay me. The VA never did. Title 19 even in CT offered us 20% of our usual fee and then couldn't understand why we would not accept their patients with open arms.
Unfortunately there is enough blame for everybody. The bureaucracy paints all doctors as money grubbing creeps so wont pay them. The private sector is willing to abandon their principles if there is cash involved.
a number of NE states have reduced the Veteran homeless population to very low numbers. It can be done if you are willing to spend the money.

@Crash
Hmmmm.....
FSPGX (Fido LCG index.) Even being 10% of a portfolio having some individual holdings and other stuff would definitely be worthy of a :)
M* performance
Whatever floats one's boat.

Hi, Catch!
The top holdings in the portfolio FSPGX scare me away, in addition to the transaction fee at Schwab. All the stocks I love to hate. I've hated them for decades. Impossible to find funds which do NOT hold some or all of them. My current holdings do hold those companies already.
When interest rates come down, it will surely aid my regional bank stock, BHB. And time will tell if BCE (Bell Canada) is a value trap. Just now, regulatory requirements have put it on the back foot.
As for positive performance, my ET is carrying the rest of the taxable portfolio on its own back, singly. My cost basis in ET is super-low. I'm loving it! And TS is facing new headwinds. But the world is not going to stop needing high-quality oil drilling pipes anytime soon.

@Crash
Hmmmm.....
FSPGX (Fido LCG index.) Even being 10% of a portfolio having some individual holdings and other stuff would definitely be worthy of a :)
M* performance
Whatever floats one's boat.

Thanks @Devo. if we are to earn the dividends, that is another 1.4%, for a total of 12% return if we the full cap is realized at the end. I will take that.
@equalizer,
"Long term 100 year 1 year rolling returns shows market up about 75% of time and probably up 80% of time using last 40 years."
Looks like you did not complete your thought or at least you did not say all of what you were thinking. Please elaborate / expand / conclude.
Thanks.

Why momentum investing work?
See (link).

More than 90% of my portfolio is with Schwab but I would happily switch to Fido if my RIA supported Fidelity
Schwab lacking auto-sweep into a MMF and Schwab MMF settling T+1 vs. Fido MMF same day can get pretty expensive pretty fast if one is not aggressive in managing idle funds sitting in cash.
Schwab reps definitely more friendly than Fido.

Once upon a time,,, the party that supported capitalism and democracy had a left and right wing. They were called the Democrats and the Republicans. The members of both parties were mostly politicians, not statesmen but they took care of the country and themselves.,,and often worked together to keep the system rolling. The Democratic wing of the capitalist part still exists,,, supporting the rule of law,, capitalism and democracy. The right wing of the capitalist party no longer exists. It has been replaced by the cult of maga,,,, which exploits racism,, sexism, xenophobia, transphobia and homophobia while replacing democracy with a dictatorship. Some of the 1% ers who could care less about culture wars support maga just so they will longer have to pay any taxes or comply with any regulations to their enterprises. Perhaps the most surprising part of this sad story is the vast majority of those supporting maga are voting against their own economic interests and their life will be undeniably worse under the regime they are hoping for.

Well said. Or, to summarize, there's the Uniparty and then there's MAGA.
It's interesting how those who every other day call this country a s---thole and bannana republic are the loudest ones wrapping themselves up in the flag on July 4 and praising so-called 'American Exceptionalism.' Irony is truly dead, apparently.

For MAXJ, looks like on June 28 they started fund with IVV at 547 and bought July 2025 puts at 547 and sold July 2025 calls at 608, which is about 11.1% upside minus the 0.5% fee and we get the 10.6% upside. Would have to check prices for this strategy over last 20 years to determine if 10.6% is at top of range. Suspect that during 2008 timeframe this strategy would pay out 2-3%?
Seems like a reasonable strategy at todays prices…
Long term 100 year 1 year rolling returns shows market up about 75% of time and probably up 80% of time using last 40 years.
.

Once upon a time,,, the party that supported capitalism and democracy had a left and right wing. They were called the Democrats and the Republicans. The members of both parties were mostly politicians, not statesmen but they took care of the country and themselves.,,and often worked together to keep the system rolling. The Democratic wing of the capitalist part still exists,,, supporting the rule of law,, capitalism and democracy. The right wing of the capitalist party no longer exists. It has been replaced by the cult of maga,,,, which exploits racism,, sexism, xenophobia, transphobia and homophobia while replacing democracy with a dictatorship. Some of the 1% ers who could care less about culture wars support maga just so they will longer have to pay any taxes or comply with any regulations to their enterprises. Perhaps the most surprising part of this sad story is the vast majority of those supporting maga are voting against their own economic interests and their life will be undeniably worse under the regime they are hoping for.

@sma3
Yes, I was still there, under Baker. A reasonable, intelligent man. He is no Trumpster-ite, for sure. Greed is always and forever a bad thing, even if it's perfectly legal.

@crash
We lived in CT, run as a one party state for decades. Budget deficits, huge government worker ( all unionized) pension and retiree health care deficits ( over $65,000 per person with a declining population). The only thing that saved them was iron clad "Guard rails" requiring a rainy day fund and any surplus to be put into deficit. Now Unions want to remove both.
Initially MA seemed much better with a moderate GOP Governor Baker ( who won by 33% margin in 2018) , although the dem controlled legislature is ranked as the least transparent in the US.
Baker stepped down. Trumpites took over GOP in 2022 and their candidate lost by 30%! so the Trumpites lost 60% of the electorate in 4 years!
Now we have a one party state. Taxes have doubled. New income tax surcharge 4% over $500,000. Mansion tax 2% on sales of over $1,000,000. People are talking about Taxachusetts again
A one party government is bad no matter who it is

@Devo,
Please check out MAXJ holdings. Investing in IVV (not Treasuries) and using a collar (selling calls at the cap and buying a put at the buffer). Would love your insight into why MAXJ has gone for holding IVV when it could have held Treasuries easily and simply, as in your post. What could be their thinking? E.g., Is it that they can not sell naked calls without holding some variation of the underlying?
https://www.blackrock.com/us/individual/products/337965/ishares-large-cap-max-buffer-jun-etf
Please comment on how the effective Cap can drop if more inflows come in and the collar for newer assets costs them more. Fund started with $10m and now at 24m Assets.
Looks like Blackrock is trying to out compete the competition. Good for us in the short run.

Thanks, @equilizer.
Innovators has six 100% buffer ETFs, four of which are July products. 2, 1, & 0.5 yr measurement period (or defined outcome period) products. We discussed about innovators earlier in the thread.
I have to check out the Blackrock product which seems to have the best cap.