With Moi I tend to work the other way around where I model the nurbs part first and export to mesh, then open modo and finish it off.

Another program that imports meshes well is ViaCAD Pro. The new version 9 also includes some basic mesh and subdivision modelling tools.
He is also about to release a Powerpack addon http://www.masterviacad.com/powerpack/powerpack.html that will also allow you to convert your sub'd meshes to nurbs surfaces which is a pretty awesome addon. All up the cost of both together will be far less than Rhino, let alone Rhino and TSplines.