In a civilian self defense situation the number of rounds fired is on avg 1.7.
Most of civilian self defense situations are decided with the first round.
This makes the size of magazines almost irrelevant.
But since the first round is usually decisive, accuracy counts even more than the number above suggests.
Revolvers with their non moving barrel, non moving slides, better balance are inherently more accurate.
In open carry situation I'd much rather have my GP100 on my side than my issue M9, even if I ignore reliability concerns ( truth be told autoloading pistols are so reliable now thats becoming less of an issue)
And with those new spring loaded speedloaders it takes me about 1.5 sec to reload. A magazine reload takes about the same.
I think the main thing driving people to the the "MUST HAVE 15 RDS +" crazy is that we all grew up with movies that are full of heros having running battles and magically always hitting.
So somehow many dont worry about accuracy anymore.
I am a revolver guy because I realize a handgun is a handgun no more no less, and I do not attempt making it a mini AR
Now if you are defending your home against hordes of Mutant Zombie Bikers then it wont be enough, but a handgun is out of place then anyway and thats what the AR15 is for.