I run the Tactical Solutions 22 upper on my single and double stack STI pistols. I went the Tactical Solutions route since they have a threaded barrel option allowing me to use a can.
I got a 22lr Kimber conversion kit for Christmas and put it on my Rock Island 1911. I have put 500 rounds through it with no problems. It is really fun to shoot!
I have a Colt .22 conversion that I use on my Series 70 Gold Cup frame. The Colt's have a floating chamber so they will recoil somewhat like a .45 ACP. The floating chamber requires plated .22 ammo, so I usually shoot bulk Remington or whatever from WalMart. Mine has adjustable sights.
I should have mentioned, I also have a Marvel on a Caspian frame that I use for Bullseye matches. It does very well with Aguila and Federal std velocity ammo.
I've had a Colt conversion for several years (bought it new), but haven't fired it for some time until ammo prices started up. It's like a new-found toy now, and my shooting pals & I really enjoy it. The Colt conversion is great, because it locks the slide back when empty: the same manual of arms as the gov't model.