Binding can definitely be dangerous if it's tight enough that you can't take deep, heavy breaths - obviously because you'll be engaging in strenuous activity. Also it can cause bruising and soreness even if you can manage to breathe heavily with it during sex.
A question about chest during sex? I was curious about the safety of different methods as well?
It depends on the situation. If I am having sex during the day I like to keep my binder and everything else on, but if it's at night right before bed I am already in just a t-shirt or nothing so I can sleep
My boyfriend is trans* and he goes bare. He says binding is too constraining and he prefers skin-on-skin. All trans* guys are different though, obviously, and not all are so comfortable with their chest.