Just an observation about converting from Sub-D to NURBS:
I noticed that the resulting surfaces or polysurfaces do not show isocureves. ("Show Isocurves: is checked on under display settings.) This has not produced any issues for me, just a curiosity.
However converting a Sub-D object to a Brep component in Grasshopper and baking the node DOES produce isocurves in the resulting subsurfaces of the polysurface.
Interestingly, assigning the converted, packed Sub-D to NURBS surface or polysurface to a Grasshopper surface of brep node and baking it DOES produce isocurves in the baked object.
None of this has led to any issues for me whatsoever, just curious about whats going on under the hood of the ToNurbs command and what impact if any this may have further along in my workflow.
See attached file and images
Selecting unpacked sometimes leads to render mesh anomalies in the NURBS surface, but this is usually easily resolved by exploding the poly and, refitting surfaces to tolerance, and rejoining, or adjusting the render mesh almost always fixes it.