Mnero, You may be right. We cannot know an outcome in advance. What I do know is that I will not take a beating from anyone especially a group. When my turn to be beaten comes up so does my firearm. If the bad guys comply and retreat it over. If not its on.
If we are playing odds I would bet that the mere sight of a firearm would end the attack.
A practice game I play once in a while would definitely benefit this scenario. Set up 4 to 6 targets in a semi circle. Open fire one shot each only as you fire move horizontally toward the first target. In theory this buys you a fraction or two seconds to complete the swing before the last couple guys can reach you. I developed this because of my encounter with the 10 plus teens.
Would be tough in a subway car but its the closest thing I've got to dealing with alot of targets at close range while trying to prevent getting over run.