H20, you bring up some very good points, but I want to dwell on one thing.
Absolutely. Shortly after buying my first handgun, I read "In the Gravest Extreme" by Massad Ayoub, and did some other research into the legal aspects of armed self-defense. One of the consistent themes was that when the threat to your life ends, so does your right to respond with deadly force. You are not a police officer, and so the only instance where you are legally allowed to take someone's life is to defend your own or someone else's life from imminent threat. The threat ends, so does the legal justification. Shoot a guy who's charging you with a knife, that's one thing. Put two more rounds in the guy when he's lying there bleeding and you're now guilty of murder.
Also, WRT giving away your keys/wallet/etc., many authors make the point that the law only allows you to defend your life, not your property. Unless someone is about to get killed, maimed, or raped, you can't use deadly force. Theft or robbery doesn't cut it.
Finally, some people have mentioned that they would only consider carrying if they were in a "bad part of town." Something else that Ayoob wrote struck me. It was the idea that if you get mugged in the ghetto and shoot your assailant in self-defense, and later get prosecuted or sued, the opposing lawyer is going to ask what exactly you were doing there at 2:30 in the morning. And then opine that since you had a concealed carry permit, you decided to go out looking for trouble. In other words, being armed gives you an even greater responsibility, if able, to stay out of the "bad parts of town."