LJ:I am not sure that the ZD back would be my preference.
Allow me to explain my longer-term plan: IIRC without going back to find it, somewhere in this thread somebody mentioned back-up, and how a 1Ds3 and raft of lenses might be the option since owning a second MF outfit is cost-prohibitive...
Well, in my case, I look at my current AFD-II body and ZD as my future back-up. Fact is, I paid LESS for them than I would have for a 1Ds3 body. At this point I'm entering MF digital and have a system I can use that generates significantly better files than the 1Ds3 can ever hope to, in both detail and color fidelity. Period. My next set-up will likely be the AFD-III body and Aptus 75S back. At that time, I have so little in the AFD-II and ZD it is more valuable as a back-up than it is as a trade in. Moreover, I have a few peices of specialty glass where the resolution difference won't make a difference in the image; like my recently acquired Mamiya manual focus 145 soft-focus lens. This lens produces a gorgeous SF effect like not other I've seen, and is totally adjustable, yet more than 22MP is going to be wasted by it. Heck, more than 11MP may be wasted, but the look is still great! I can see it left permanently attached to the AFDII/ZD
Another point that I think Marc may have alluded to briefly: If you are hand-holding these cameras under ambient light at speeds under 1/500th, I doubt you are going to get more than 22MP of resolution data into the file anyway. Under strobes hand-held or on a tripod, different story; improved tonality and DR with the newer/larger backs also a different story, so there are certainly reasons for owning the better backs.
Howeverbut... This does not solve the leaf-shutter, working under studio lighting scenario for me. The good news for me here, is 1) I rarely do this type of shooting anymore and 2) the studio I use whenever I need to do studio shoots, has a full compliment of Hassy H bodies and my choice of Leaf Aptus 75 or Hassy H39 backs at my disposal to borrow... (Yes, I know that's a sweet deal.) So for me, I kind of have the best of both worlds without having to actually own the two completely different systems...
Lastly, Mamiya actually made 4 leaf-shutter lenses to be used on their manual 645 system; a 55, 70, 80 and 150. They are manual focus lenses and a cluge to use -- double cocking, special cable release, limited to 1/30th through 1/500th -- but for static subjects like table-top or mixed lighting interiors, a cheap way for Mamiya owners to solve the leaf-shutter/flash sync issue.
Cheers,