Two things stick out to me from my experiences:
1. People shot in the torso with a rifle don't always "stop" right away.
2. I was never in a gunfight and thought, "gee, I wish I had less ammo."
I base my carry weapon choices on those experiences. My home defense weapon isn't a handgun.
I usually carry a M&P compact 9mm, so 16 rounds of HST on tap. If I go small, and it's not often anymore, my 45 shield is only one less round than my 9mm shield, so I carry that. I'll take 7 shots of 45 over 8 shots of 9mm.
I'll probably get a Shield + and call it a day.
