ALet me start by saying that I am planning on piping black decorations on white SMBC. I don't know, but i assume that it would be very difficult to tint SMBC black. So my question is which would be better to use? Would one be better to avoid bleeding over the other?

AI pretty much only use SMBC, unless it's ganache. I don't think I'd ever consider piping black anything on top of it, but if I had to, I'd use colored food powder to dye it.

AI would not try to tint smbc black. Use royal icing. Powdered or gel I've done both

I actually got the SMBC to go black! First I started with cocoa powder (because the cake inside will be chocolate anyway), and then I added a combo of powdered black color and gel super black. It worked. Now to see if it bleeds into the white SMBC. I feel like it is safer to use the black SMBC rather than royal, but I could be wrong! 

AIn case anyone wanted to know, the black smbc piping on white smbc worked out perfectly. No bleeding anywhere. In July, in NC! I did keep it chilled and boxed before delivery.

great work, lovinspoonfull