I have to admit, I'll always pay a premium for an unspoiled set versus one that has been tinkered with (or even competently restored) by someone else. For me, the challenge is all in the restoration. I lose interest pretty quickly after that's done. Likewise, I would never buy a set that was fully restored by someone else (dang -- they got all the fun!).
Which makes me a sort of hypocrite, I guess. I want the unspoiled goodies for myself, and then I promptly destroy the set's originality (from a preservationist viewpoint) by restoring the electronics and sometimes the cabinet. My rationalization is that most of my stuff is not especially rare or valuable, so nothing precious is lost if I make it work.
I do understand and appreciate the preservationist ethic. Elli Buk's collections were auctioned off last year, and I'll bet most of the buyers were delighted that he had left those many interesting objects in the same condition as when he got them.
I don't own any pre-war TVs (or the equivalent class of radio). If I ran across something like that, I'd certainly give the question some serious thought. I do own a couple of radios that I have decided not to touch at all, except for gentle cleaning. They don't have great monetary value, but they're worth more to me if I leave them alone.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html