I've got a herniated discs (and a couple dessicated) in my cervical spine. Lead to shooting pains in my shoulder and tricep. Most guys I roll with are aware of it and don't jack up my neck - I'm sure if you let your future training partners know, they will be good about it (find a school with responsible instructors and good people). Sucks because it's frustrating and makes me feel like a total ***** sometimes, but gotta keep an eye on the big picture - can't work/train/live tomorrow if I get hurt seriously today.
Also how prevalent is the attitude of "you must feel how bad a submission can hurt you to really understand it" or w/e variation on the "tough guy" approach to training. I see these two questions as somewhat related.
I can't really afford a 2nd injury to the same shoulder and while there is no MA that interests me more to start than bjj, I don't know how realistic i am being.