Where all things are equal in terms of how proficient the good guy and the bad guy is in shooting ability, the bad guys element of surprise and mindset puts him at an advantage.
Thankfully many bad guys do not train or use the Ghetto method of gripping a pistol..if the side of the frame mounted sights are missing you have a better chance.
I don't see the argument has moved, it is part of the equation and overall topic... If you have a .50cal bear pistol it's useless if you don't fire it.
In all encounters the factors have to be weighed up, the best gunfight is of course the one you never have.
Mindset, well there's a great topic

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How many people have that "will to win mindest", how many people walk around oblivious to their surroundings plugged into iTunes or updting their farsebook status....how many people think it's better to be a victim than fight back in any way?
A proper course - not a one off class - will cover all of that, and more if you're lucky. Carrying a gun is not in itelf a miracle cure you MUST train and keep training, like martial arts only gun handling is quicker. Yes there are always if's buts and any amount of "maybe" situations where you just are not going to win for whatever reason: the number of aggressors is now nearer two than one in any event - statistically speaking.
In most discussion of this ilk the assumption is the bad guy wants to kill you - the state of mind of the aggressor is important: does he just want some coin for food or drink or is he intent on raping you, your wife and kids..opposite ends of the spectrum.
Many baddies will use the gun as a prop, it may or may NOT be loaded, that of course is your call, BUT the underlying thing is they do NOT expect to be challenged and invariably they ARE not well trained, if at all. That's the whole point of carry - it's a last resort tool when all else has failed. As with all tools, use the best you can afford and handle.
Sorry just saw your last post ordnance ...I am working on handgun and personal self defence for civilian use as that was the initial topic ...Israel giving civilians the ability to defend themself.. Obviously the wider the topic the more variables.
Agree the USA loves .45 because that was military issue like since what, 1911??? The 9mm is obviously lighter and you can carry more and the Beretta 92 standard issue is 9mm : there re few .45 cal pistols that have double stack say 15 round magazines (Para Ordnance make a good one).
A lot comes down to perosnal choice: I shoot .40 SW and 9mm - the missus has a 9mm and a 12g for self defence.. no exotic ammo, not allowed..Just FMJ for the pistol and buck /slug for the shotgun.
Agree re the shotgun - 00 buck is 9 x pistol cal balls hitting the body, not passing through and effectively transferring energy.
And very hard to repair....
Back to stopping power: "What do the police use"..there's a guide for civilians. There's just so much to this. How long is a piece of string - WHO are you stopping from doing what???? The determination / size / state of mind of the aggressor is a factor.