I should note this post was engendered by a little bit of repair work on already-mapped models...which proceeded to give me the usual frustrating problems in retaining and repairing said maps.

It's a toss-up, now, whether it is less annoying to stop a model half-way in Carrara, export, use UV-mapper, re-import, then continue working....or go into Carrara's UV mapper, split verts, drag everything around to fix the stupid mapping errors, then continue working...