I'm white, and I've seen em twice... once for an opening (D'Angelo) and once on the OKP tour (same show emil is talking about I think... in DC, they burned a flag/bandana).
Some people have tried to say that DP "wouldn't slap my hand cuz I'm white" and all this nonsense. I don't know if it's true (I personally don't see them being like this)... but really, emil's right, they play to a pretty white audience half the time. Most of the people who go to DP shows are pretty cool anyway, they're not gonna give you a hard time.
Do whatever you feel comfortable with... but to answer your question, they're not gonna take out their "first son" and leave you on the ground.