Well, we're just going to have disagree on this one. However, are we talking about trying to shoot someone from across a street or a room or what? If the distance becomes too great, one may just consider you wanted to shoot the perp.
Yes, I'd take a .45ACP over a rimfire any day of the week. I'd even take a .357 Mag as well. Key to avoiding trouble is to stay away from it. However, in most cases, an attacker is not in it to get hurt, regardless of caliber and they tend to break off once they find the "victim" has any sort of firearm and is willing to use it.