I started a revelution in my gym,
i was the first to do them, after seeing the movie Blood and Guts, Dorian Yates, and now everybody does them.
I prefer dumbells, but that's because the belt is to small, the owner has bought own confirm his own size, and he has Asian origin.
About the TS question, choose a comfortable width. The smaller, the more you hit the triceps, but some people get injuries/pain if they dip to small.