In my opinion, which isn’t worth a bag of fog, it’s all about how many accurate rounds you can get on target in a short amount of time. Someone who can get 10+ rounds of .22LR in centre mass in just a few seconds is more likely to survive than someone who just manages to squeeze off a round or two of their .45 that only grazes an attackers arm, or a 12ga slug, or a .223, or whatever.
If you train and get good with your firearms, then being able to accurately put rounds on target would make up for having a smaller round. But, obviously in the real world you wouldn’t have a paper target, you’d have someone who is trying to do you harm with whatever they have at their disposal, thus meaning you really do have to become one with your weapon system. You may not have time to get a proper stance, or control your breathing, or tough the trigger just right. You might have to be shooting while getting to cover, so practice drills like that.
In a similar side to this, smaller rounds means you can carry more of them. Maybe those few extra rounds may just save your bacon.
Again, just my opinion on the matter.
Canadian Patriot. Becoming self-sufficient.