CAD is very interesting. Clean booleans, every time, and mathematically perfect surfaces. For some operations, it can't be beat. But it's hard to swap between polygons and CAD surfaces so you have to pick up front ... choose wisely. :)
So for someone that knows absolutely nothing about CAD, how is modeling in one of these package different from using Max or Maya...? How do you describe a surface with something else than polygons...? *scratching head very neat art on those 2 pages Beef.