We had a PC who got a beatdown from 6 Aztech security guards with stun batons. He got hit 3 or 4 times with a stun baton. Is the -2 cumulative or just a one time deal?

This came up recently with my group as well. We just made the time cumulative not the -2. For instance, if you were hit and were effected for 4 rounds the first turn, and for 3 turns the next combat turn you would now be affected for 6 remaining turns (3+4-1). It's not official, but it's how we dealt with it.

I dunno what I'd do, personally. I've taken a pretty good jolt off a car's alternator (which packs as much punch as a lot of tasers), and I'm pretty sure repeated hits would make my day a lot harder. Of course, that could also just be the stun damage talking... your solution sounds pretty reasonable.