Coming originally from Avid where all color is broadcast safe whether you like it or not, I'm not sure when to make my color broadcast safe in Premiere. I understand that for web video and things that will never end up on a TV broadcast safe is unnecessary, but if I'm creating a video to be delivered on DVD should I make everything broadcast safe?
Based on my experience, you should always try to have your luminance levels between 0-100, anything beyond could get clipped somewhere in any delivery chain.
As for color, it's more lenient. I think over saturated reds get destroyed first when going to DVD and displayed on flat screens.
I never worry about it.
I always make sure I'm at least between 0 and 100 on the RGB parade