Don't run from a sniper, you'll only die tired.
Now I believe that we can safely rule out long guns (rifles and carbines) from this discussion. Handguns; single shot, semi automatic, revolver, and double barrel, seem to be the weapon of choice for muggers, creeps, and all sorts of unsavory characters.
I truly believe that most martial artists will not be acosted by an attacker unkown to them. Muggers and rapists prey on those whose body language marks them as an easy target. Anyone walking with situational awareness, and confidence, is probably much safer than the guy studying his shoes.
Now as to an attacker who is known to you, only you can judge. Someone who knows you, knows that you're a martial artist, will already be bent on murder or have a mind so clouded with emotion or drugs that they can't be reasoned with effectively. What do you do?
I try to live my life so that people don't feel any need to erase my existence from this earth before old age takes me. But say you have a former lover/spouse/teacher/student/family member/or postal worker who wants to kill/maim/hurt/stab/or mess your day up something fierce? How well do you know this person? Will your mind be clear and calm? Will you try to avoid hurting them and yourself? How much do you value your life?
In my opinion train to disarm an attacker. But only attempt it when the attacker leaves no other alternative. If you are on the street and the attacker wants you to get in the car, DO NOT GET IN THE CAR!!! Remember this, every situation you walk away from alive is a win. If the pistol goes off by your ear and you suffer permanent hearing damage? Oh well, at least you are still alive.
So keep on training and pray (if you're into prayer) that you never have to use it. Best of luck to everyone. On a side note, didn't the Okinawans creat Karate because their Japanese conquerors didn't allow them swords? I wonder what martial art will be created when we are no longer allowed firearms?
what you do,
when it counts.