I'll place reliability over accuracy. It doesn't matter if you can put every round in the same hole if you have problems with it feeding. Just keep putting different brands thru each one until you find which they like the best. Get spare magazines for whatever they will carry also, I carry four at present, and will be getting two more.
I am curious, is the reason they will be shooting .22s because that is all the range is suited for? If they are going to carry I would say they should use the piece they will be carrying. I qualified with my Ruger 9mm, and most of my rounds made a doublefist size hole in the middle of the target. But it's heavy for me and my bad joints, so my carry wound up being a Bersa .380, which is 100% reliable no matter what I put thru it.