Personal choice would be a G-23 as it is a bit smaller, and you can use G22 mags in it. But if you already own a G22 I certainly would not go buy
a G23, really not cost effective.
What ever you carry, practice with it and when you are comfortable, practice some more. I used to wonder why a transition course too so many rounds until I had changed weapons several times in the course of my INS/DHS tenure. Usual transition at the academy was about 2500 rounds over fifteen weeks. Transition at the duty station was 1500 when we went to the Beretta 96 from issued wheel guns was about 1500, and when the USP Compact/2000 came along it was between 1500 and 2000 round depending on how close we were to Oct 1 (new physical year).
Thom Braxton
SWCA #1474