I think the possibility of article rehabilitation is probably the best reason to do something like I suggested. Otherwise though a relegated article in my mind should be largely like a deleted one in that the main wikipedia can't link to it - but external links will still take you to the page which would be clearly marked as not in the real wikipedia.

I agree with your point about the extreme deletionists, I think if they couldn't irrevevocably destroy the work they would be a lot less interested in pursuing it with such vigor.