funny, I was thinking that CastAR (now Tilt Five) would be a good compromise for that. Having your CAD display in front of you of you, the reflecting mat on the side and no too intrusive glasses. So that you just have to turn your head to see the 3D. You don't really need virtual reality when you're just working on an object, you just need a bit of 3D to help you grasp the shapes.