SubD-Project: reasons for editing the Limit Surface?

My understanding of “compatible Brep object” is an object that can be manipulated with all Rhino tools.

If we can manipulate vertices of this SubD mesh with Gumball and SoftEditSrf, and we can translate the SubD mesh to normal mesh and back, the SubD mesh will be useful method of making organic surfaces.
Here is clear explanation of subdivision surfaces: https://www.youtube.com/watch?v=ckOTl2GcS-E

Sure, but that is only the first part. More importantly the model can be used in any downstream application that does not support SubD objects. That is most CAD, CAE, and CAM applications. Most of those applications require spline (NURBS) breps.

Yes. That is the UI bit. No hard math involved… but it is a major coding and testing project.

examples of animated subdivision splines:
animals: https://www.ibiblio.org/e-notes/Splines/animation.html
fractal terrain: https://www.ibiblio.org/e-notes/Splines/terra/subdivision2d.htm
fire: https://www.ibiblio.org/e-notes/webgl/models/fire.html
clouds: http://mrdoob.com/lab/javascript/webgl/clouds/

Those are amazing. I loved the clouds and the parrot.