I had a 21A and still have the single action 950 in .22 short (one of the rarer ones with an extended barrel). My particular 21A was in .22LR and I would not suggest one as a carry gun. It was not reliable enough with any ammunition that I tried to truly trust, though was a fun little gun to shoot. Mine worked with bulk pack cheap ammo as well as anything. I shot mine extensively.

The gun as no ejector, it relies only on blowback to clear empties. Thus the standard clearance drills for getting rid of a jam are useless. It is also a problem when you get a split casing or dud which often happens with .22 ammo. I'd rather have one .25 if I had to have one, since the .25 ACP goes bang more reliably (I don't like my life hanging in the balance on the vagaries of rimfire ammunition ignition). If for some reason I had to have a small .22LR handgun, I'd find a 317 of early (prelock) vintage and enjoy the 8 more or less for sure rounds of .22 on board it.

My wife actually carries a Lorcin .25 in a Hello Kitty thing meant to carry a Nintendo DS. It is no more troublesome than my old Beretta .22.