I use both. Bump for tiny details, displacement for the very noticeable, larger ones (but ONLY if those details are large enough to warrant it.) ;). Never had a problem using both, because both have completely different information. I have a lot of respect for stewer and what he says, but in this case I don't agree...hehe.

For a for instance, I'd use bump for skin pores, but I'd also use displacement for large scars if that helps.

Laurie