Well I would like to see more interoperation with Rhino5. Yes sorry, but my clients and colleges like it.
- So Blocks and Instances (also in .stp) could be handy.
- Layers and colors.
- more control over what is in the scene.. trash it out and such.
- that said I also do imports and .stp import could need a speed up.
- for export I wish 64bit support in OsX, or a way to split files up, so everytime memory limit is close, just finish that part and create another OBJ.. easy?

I second the wish for better fillet tools.