This is an interesting thread.
Personally, I am a 2nd degree black belt in TSD and am in pretty good shape. But, I will not engage in a fist fight with some idiot out in a parking lot. I've seen too many street fights go bad with a lucky punch or kick. I would be more inclined to OC-spray the idiot and then call the Police. Of course I would draw my firearm if there was a threat of violence that OC couldn't resolve....like several people trying to mug me.
"I like these calm little moments before the storm (Stansfield, The Professional)."