I guess I'm also interested: I may not be a "serious modder" in that I've publicly released next to nothing, but I do enjoy pointlessly tinkering with 3D models and couldn't figure out how to do it in D:OS. Which was frustrating as it was possible in Ego Draconis, if fiddly, so moving to a game that doesn't support 3D modding seems like a step backwards.
I always grimace when I see GR2 formats: I'd previously assumed it was just because I hadn't figured it out rather than it actually being inaccessible to end-users, which is a bit depressing.