I think one of the main things a bigger carry gun has going for it is that you enjoy shooting at the range more and become more fluent with it. Yes you should always train with your carry gun but a lot of times the micro guns are more of a chore to shoot a bunch and as such probably don't get as much range time as they should. If you can pull off carrying a large gun and it's a dream boat to shoot at the range you are ahead of the game.