Quote - 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.

One of the first things I learned about computer graphics: if it looks right, it is right.

Using bumps and displacements separately makes sense in renderers that don't use micropolygons, since there bumps are of a higher resolution than displacements. In FireFly however, small displacements are only slightly slower than bumps and you're not gaining anything by separating the two as opposed to using all displacements.