I looked into it a little just now and it seems the SubD aspect is a seperate modeling toolset from the NURBS modeling tools. I didn't see anything showing how they integrate to form a hybrid SubD/NURBS Modeling toolset beyond what most DCC apps provide, which are seperate Poly/SubD/Spline/NURBS toolsets. I saw great tools for modeling hard surfaces using the SubD modeler, but not much on how it handles booleans and trimming, the stuff that makes NURBS stand out to me. The closest thing I have been able to find to a hybrid SubD/NURBS tool is Maya, only because it can convert back and forth between the different surfaces well.