Hi David
Have you had a bad experience with Diascopes? When I researched them before buying there were many excellent reviews and articles which along with the Zeiss brand reputation, convinced me to buy. Allbinos and respected birders/naturalists gave it superb reviews and in its day (only a few years ago) it was regarded as one of the best scopes.
I'd be surprised if Zeiss, with their quality control, guarantees and high craftsmanship would allow sample variation and questionable quality in such a flagship product.
I've tried Kowa, Nikon, Hawke and Opticron scopes and with the 20x75 zoom I found the 85T*FL to live up to its name as an impressive bit of kit.