The RB and RZ are the same as far as bellows extension etc. The RB really doesn't have any safety things like the RZ does, I think you can even take the lens off while an exposure is happening haha! (I could be wrong, but I know you CANT do that with the RZ, it actually locks the breach). I think you have to wind both the film and the shutter on the RB, on the RZ the one cocking motion winds both the film advance and the shutter/mirror in one motion. I clearly don't have an RB so I can't be sure of the rest. I do use a 70mm back which is an RB back and I have the "G adapter" which adapts the mini-graflock attachment of the RB to the fancy rotating back system of the RZ (so yes the backs that attach are completely different. For the RZ there is a "rotating back" option you can buy separately that didn't come on the original models, I don't know if the Pro-S version has that included or not.
Originally Posted by analoguey
Basically the RZ is a much better design in almost every way with added "features" with one huge exception ... the RZ is electronic so it uses batteries for the shutter, not true for the RB so is your battery goes dead, you can use the RB in the middle of the night on a 2 hour exposure and have no worries, for the RZ it only functions at 1/400 when the battery dies, which is no help when you're 30 minutes into a 2 hour long exposure and the battery dies and the shutter closes on you... yes this happened to me ... twice.... lol
But all the safety features of the dark slide pulling prevention etc are really handy. I can't tell you how many times I've forgotten to pull the dark slide out with the 70mm back and gotten a blank picture, if this were a normal RZ back, the camera body wouldn't let me take the picture and would have a little glowing red/orange light with a picture of a dark slide...
Also the optional viewfinder you can buy that has an exposure meter and auto exposure features is a nice touch, and is way fancier than the RB's one if it even has an auto exposure option, not sure.
I mean, that's why they make new models because the new models have more /better features...
I don't know anything about the auto winders you can get, I shoot film so I can slow down... haha
Hope that was helpful.