I've had a bj and sex with two women with an audience of around 18 people before now so no problem at all.
I'm no Brad Pitt, I dont have a 16 inch dick but I am comfortable with how I look and the size of my dick so couldnt give a flying monkeys arse what the other guys in the room are like. I've been in group situations with guys with dicks both half the size of mine and twice the size.
Who fuckin cares? I'm not there to shag the blokes, I there to have fun with the girls.
I am with James on this I could no way perform with another man in the room - 2,3,4 girls no problem.
I certainly would not be able to perform in front of an audience