I'd love to carry one of those while playing real paintball (in addition to a *real* paintball gun). Nothing would give me more of a thrill than to circle around the other team and start taking out players with that thing.
I'll bet it's quiet Then again, would the other person even feel it to know they were out?
Nothing beats completely circling around a bunch of newbies on a speedball course and sneaking up behind each them, one by one, sticking your gun against their back and screaming "surrender!"
This might be nearly as fun as that though, and would avoid my getting shot by someone whose answer to surrender is "No!"