I can not understand WHY if you have your ccw and weapon would you be willing to get in a physical altercation. There's no way a cop would try to get physical with a BG of the same size before pulling his weapon non-lethal or not, a civilian is afforded this same recourse in my opinion. Most of the people I've met that are FLUENT in martial arts are also the last ones ever to get in a fight. I've served in the Marine Corps and seen ears ripped off and teeth knocked out because people with so callled skills got into fights as opposed to scaling down the situation with other means.
In reference to the orginal question I think walking/running away is the best recourse. If leaving is not an option and you feel that you are in eminent danger and you are carrying by all means drawn down on the threat, shoot if necessary,call the cops absolutely nomatter what.
Sparring and fighting are two totally different things, this being stated it absolutely makes no sense to me to be involved in a physical confrontation with someone when you are carrying,the risk of losing your firearm is too great IMO.