Just my opinion. I think people way over think this stuff. For self protection, anything that will shoot out of your shotgun to the attackers face will stop the attack.
Who cares if he is dead or not.
I think you might be UNDER thinking it a bit. Anything that can hit someone in the face will stop the attack? I've been hit in the face with #6 bird shot. It didn't even stop me from enjoying my day....