It would be very useful to have some more _Sel commands for SubD.
Examples I’ve seen in other software are for naked edges and for creased edges. Internal uncreased edges would be great too. Another good one would be for holes (naked edges, excluding external border.) Why would we need holes when we already have naked edges? Convenience. There are a number of ways to sort holes from exterior naked edges, but some of them, like simply using the length, can fail: it’s possible to have a hole with a longer border curve than the exterior border of a SubD.
Maybe more? I’d also like to see these options on the SubDEdges grasshopper component.
Also: Adding _DupVertex command, history enabled, would be really useful. Either that or an option when selecting points in grasshopper to reference a vertex. What for? For example: creating planes from chosen subD vertices using the Plane 3pt command, using the planes to generate geometry for altering a Brep created from an editable subD.