I have been using 2D-3D a lot lately. One bothersome issue is that it is not apparent until after you are well into a conversion that the tolerance chosen was too small. Even with dwg from the same company you will see a big difference from drawing to drawing on vertex closing. So you either end up tracing or redoing the import. And no, I didn't think to use repair first.
The other thing, and I may just be missing something, is that while align is very powerful, the first thing that needs to be done is to mover the front view to the front plane, etc. Now if align could just be made a littel smarter this would be very helpful.