Also, way I look at it, if you've got three guys shooting at you, you're not likely to live long enough to expend all the ammo in a 15-17 round mag anyway...
Trick is, to increase the odds that the other BGs will flee, you've got to very, very quickly determine who the leader of the pack is and plug him FIRST. Seeing the rabble rouser go down first hopefully will result in the others scattering, but as always, there are no guarantees. But I do agree, if you end up in a situation with 3+
determined, suicidal attackers armed with guns themselves and there is no cover or even concealment in sight you are likely screwed, regardless of the handgun you carry. I read a statement years ago that in such a dire situation (outnumbered, 3+ attackers with guns not backing down, no cover, no where to run), the additional rounds in a hi cap semi auto aren't going to save you, but you'll at least be able to take more of them with you.
It is the indian, not the arrow. As always, a skilled handgunner that can keep their wits more or less intact can make about any gun that is mechanically sound work for them. The opposite is also true. I've heard some opine that the most common failure in a gunfight is running out of ammo. Others say it is running out of time. I tend to agree with the latter, which is indicative of a lack of training, proper mindset, etc. "Software" failures, in other words.
IMHO, landing that first shot is critical. Not only will the fight hopefully end sooner, but you won't be spraying bullets all over the landscape (I'm in a fairly urban setting, so to me, missing is NOT an option). I therefore prefer handguns that are good point shooters
in my hands. For me, those handguns happen to be S&W K Frames with 3" or longer barrels, L Frames, N Frame, the Ruger Six Series and 5" 1911s. For the next guy it might be Glocks.