I'm looking to get a fullsize 1911 .22, partially for practice with something lower recoil, partially due to ammo cost, and partially so I have a cheap 1911 to play around with parts on. I've heard really conflicting stories about the GSGs. Can anyone specifically recommend (or not recommend) them, and why? I've also been looking at the Sigs, but I don't hear any feedback about those, and they're slightly more expensive. Are there any other options I should consider?

There are several alloy construction 1911 .22 clones out there. Regardless of who put a name on it they are all made by umarex. If you already have a 1911, my advice would be for not a ton more money get a marvel conversion kit. Much better quality.

As was said earlier, the Sigs were actually GSGs. Sometimes I wish I'd bought a GSG target model when CDNN was blowing them out for under $300. I think I saw the GI version for as low as $240. Never saw a Sig marked one that cheap.

PM me if you already have a full size or Commander frame and want a GSG/ATI conversion kit with one mag. I paid about $280 for two of them several years ago, one's still NIB.

EDIT: Sportsman's Guide has whole guns for $245, I thought they were out of production. That's a decent price.

Lots of reviews out there to read.

Bought the Sig 1911 in 22 a few years ago.
What a POS. First it looks like a 1911 but the internals are not.
When I used it from a Kydex holster the finish came right off.
Accuracy is crappy. (note some friends shoot it better).
The only reasons I keep it is to loan out to new shooters and for when my grandchildren get older.

Buy something else. If it was worth anything I would put it up for sale.

I've got a GSG.  I love it.  Yeah the finish sucks, and the sights seem janky, but usable.  Easy swap on them.

I had a GSG conversion and quite frankly it sucked, got rid of it a long time ago.

I now have an Advantage Arms 1911 Target Conversion mounted on an Auto-Ordnance frame and it's extremely accurate. It is a bit fussy with ammo but once that is sorted out, actually don't be like me and just follow what Advantage  Arms recommends and there is no problem at all.

If you just want to plink the GSG is ok, but not if you want to get even half way serious about target shooting.

I had the Sig. Man I miss that thing...

Just got one of these, had a bit of a time putting in a flat main spring housing as the three leaf spring got loose. Once I figured that out it was GTG at the range. Shot old Remington Golden bullets and had one FTF early on and these were grungy old, next up some  Blazer .22 all shot fine. It has the tallest sight in place and is about 3 in high at 25 yards. Accuracy is fine by me as it's a low level practice piece for the 1911s.

ETA: It's a SIG /ATI