I just got off the phone with Jim. He said that they would not give me my original screen, even though they don't use it to make the Proscreen, because the screen exchange is part of the pricing. I asked him whether I could pay extra to retain my original screen, and he said that no one had ever asked him that and that he was not prepared to offer that. He did give me assurance of two things that others might find useful to know. First, there is a 10-day return policy on screens. So if I receive my D700 and don't like their screen, I have 10 days to return it for replacement with my original screen for no service fee (although he did mention they will charge me again for shipping if that occurs). Second, the screen installation does not affect the Nikon warranty even though the D700 screen is not interchangeable according to Nikon. I don't see this in writing anywhere on their site, but given how long Brightscreen has been in business, I'll take Jim's word.
One other thing he mentioned is that their return policy on cameras is only 3 days. I hadn't realized that, but it won't affect my decision to order.
Regards,
Amin