RB vs. RZ: I love my RZ, but I only got it because it came along for the right price. I'd be just as happy with an RB. The things that I think are much, much better with the RZ are the single-action advance/cocking, the 110 mm 2.8 lens, and that fact that the RZs will take both RZ and RB lenses, while the RBs will only take RB lenses. Having the shutter speeds on the body is a minor convenience, and the backs not having as many seals is great as well. Having intermediate shutter speeds on the RZ Pro II must be nice as well. I would search for both, and take whichever comes along first for the right price.
Pro II vs. Pro II D: I would just get the Pro II if you want to shoot film only, however, if you can get the Pro IID without paying much of a premium over the Pro II, why not?