the ZD camera will not be released in the US...too many problems....the ZD back is faster ( just a bit) and supposedly has slightly better imagequality (hard to imagine how or why)...i guess this will help mamiya with the sales of their bodies....there really is no need to sell the ZD body if the back is only 9000 list (which might come to quite a bit lower street price?)...it will work on the 645afd and on the RZ with an adapter, which makes the back rotatable! so with prices on ebay as they are, this is a way to get a complete system (with lenses, maybe even 645 and RZ!) for a price comparable to a canon system...with better 50 and 100 quality....i guess any competition is welcome...even if it is 3 years overdue...