althought it is true that fs2/pof/converters don't have the best shadings possible, what you are reporting are problems caused by you doing something wrong
cob2fs2 (or modelview) can use SMOOTH or FACET
pcs can use AUTOFACET or FACET
this mean that if you convert a smoothed object with pcs, it will be faceted, if you convert an autofaceted object with modelview, it will be faceted
Faceted is good for blocky elements, but when faces are not flat (like with rounded elements) you'll see the lighting on a per face basis (you'll see the borders of the polys)
When you have rounded elements you have to go with autofacet in pcs or smooth in modelview
If you have a complex solid object you MUST use smoothgroups, or it will suck.
Smoothgroups means that you don't use the same shadings on the whole object, but you use different autofacet angles in different parts, or you make some parts faceted and others smoothed.
If you are using submodels you'll have less shading problems (which doesn't mean that you have to use submodels)
Don't split you mesh in subobjects untile you are forced to (subobjects' shadings is screwed in fs2)
If you don't want to bother using smoothgroups you'll have the best results by using autofacet on the whole mesh, with an angle around 45-60°
Sometimes, it happened to me, pcs give problems with autofacet: it converted the mesh with a very low angle, no matter what angle I defined, and the result was similar to faceted shadings, I could see the edges of the polys, in this case you'll have to use smooth shadings and modelview.