It is true that a few early Dynatechs de-bonded but I think I'm right in saying that this was a problem with very early frames, ie pre 1991 and Raleigh jumped on it pretty quickly to resolve the issue. The serial number of a Dynatech starts with A, B, or C... denoting 1990, 1991, 1992 and so on; So if you look for a 'c' frame you're not going to have any trouble, but lets be honest, how reliable is any 20yr old MTB frame from an unknown source??
As for retro coolness, they're British, Titanium (mostly), early 90's, bonded and lots of them have cool paint jobs... what could be cooler?