@sonicus
Great question.
This instrument has had a prior repair at the neck/headstock joint. According to the prior owner, the repair was prior to 2002 and is very stable, but it is not so pretty. If I were only concerned about sound, I'd leave it as is except for maybe a fret job. That said, I think there are some things I could do to make it prettier for not much money (clean up the hardware, prettify the humcanceller, replace the 12th fret inlay).
On the other hand, it could be completely restored to like new condition. It would be beautiful, but I don't think it would sound any better. Also, then I'd have to worry about bumps and bruises more than I do now. Not to mention I'd be without the instrument for a while (my only Alembic) and there is the added cost of a total restoration, although I am sure it would increase the value of the instrument.