Moi's n-gon meshes are not suitable for subd smoothing because the extra vertices which create the n-gons are not matched up to the vertices on the coneccted faces. The exceptions would be more simple objects such as a cylinder or box. But then you might as well have modeled them in subd to begin with...

NPower makes a 3dsMax plugin which translates trimmed nurbs objects into quad meshes which can be smoothed as catmull-clark subd...

jonah