not sure bro, but have you tried the surface modifier? i think cad comes in like splines right? can you post up some pics and give maybe a little more detailed explanation of a specific example of the problem? im guessing around a lot trying to figure out where the density problems would be. :shrug:
Anyone? Also, I've been looking at retopologizing recently. From what I gather, you create a lower poly mesh by snapping the new surface over the underlying high poly one. What if I wanted to do something similar with a HP sub-d model over a CAD model. Is there a way (as the smoothing changes the shape)?