You will end up with just kribs if they pair off. They become homicidal killers. Just one pair wiped out a good size school of albino corys in one night. The ones that were alive in the morning only lived a copy more days.
They might not bother the barbs (mine don't bother my dither fish, but I don't keep them with other fish bottom feeders), but I wouldn't put more than one pair in there for aggression reasons - they could kill each other.