Most arguments of "stopping power" seem to mean "Kill power". If I'm using a .410/.45 revolver I'm not trying to kill. I only want to stop the attack. If I truly want to kill I'm shooting something with a 7.62 mm slug MINIMUM through a 14 inch barrel or longer. (30.06 is my first choice)
If I'm using a handgun my preferred results are 1:The sight of the handgun will give the perp second thoughts, 2:One shot will be enough to cause them to flee whether they are hit or not, 3:If I have to shoot them it will slow them down so I can get away or, if in my home, they will be disabled from further action.
Two things I would prefer to avoid 1:An extended gun battle, 2:Killing another person, even if I am "in the right". That is why I would be inclined to fire multiple rounds of shot or a self defense disk/shot round in a handgun.
Just my thoughts, take it for what it's worth.