Yes, we are all well aware of Dune3d. I'm a big fan of Lukas K's work. In fact I wish he had done our GTK port first, and then forked Solvespace to use Open Cascade to solve the problems he needed to address. That would have given me this task for free ;-) We are not currently planning to incorporate OCCT but to simply extend and fix the small NURBS kernel that Solvespace already has.
Can you comment on the business case here? I think there was a Blender add on that uses Solvespace under the hood to give it CAD-like functionality.
I don’t know any pros using Solvespace by itself, and my own opinion is that CAD is the wrong paradigm for most of the things it’s used for anyway (like highway design).