Max Smirnov has been working on a subd converter for Moi, go here http://moi3d.com/forum/index.php?webtag=MOI&msg=6674.68

Subd modeling for nurbs is now becoming available in several applications. I believe the new ViaCAD Pro (less expensive than Rhino with T-Splines), as well as FormZ have this ability now.

Also check out Resurf3d, they have a stand alone converter that will take an OBJ with quads and convert it to a smooth IGS surface and its only $80, but you can't edit the shape of the subd in the converter, you would have to go back to your poly modeler. Not as ideal workflow, but less expensive.