...Personally, if I feel that I am facing the threat of injury or death, I will shoot to kill. (Sure, I'll try using the weapon to warn someone off first, shoot into the air, etc., but ultimately I will be prepared to kill.)...
[1] You might want to reconsider saying that you shoot to kill. Those of us who have taken formal personal protection classes at places like Gunsite or from instructors like Massad Ayoob are taught that we shoot to stop. And those of us who teach personal protection teach that we shoot to stop. Yes, effectively shooting to stop may require inflicting multiple wounds to vital parts of the attacker's body, which might well be mortal wounds. But the goal is to stop, and if the attacker stops and survives, that's a fine result.
[2] Warning shots, like a shot in the air, are a very bad idea. The bullet has to wind up somewhere, and that may be somewhere you don't want it, like in the body of your neighbor's kid or the old lady in the dress shop down the street. If the attacker stops when he sees your gun, that's a fine result. But if you have to shoot, you need to shoot to hit your target, not just to scare.