Most of these years, in 645 format, I've had, loved and still am a big fan of original Pentax 645 (not the follow ups and I do have the NII). Then I went for Mamiya 645 1000 when price was right on a package and realized how much WLF was amiss in my hands. Both lack interchangeable backs, so there came the ETRSi.
Now it is hard to make a call which one to take for a walk. Pentax annoys me now a bit with fixed grip and permanent motor drive, so it is noisy at all times and much larger for the grip, but fantastic camera in all other departments.
The ETRSi is a revelation in many ways, very positive one. I actually started on Bronica brand with EC (nearly got the S2A at first), which is so sweet in every way and much better controlled mirror than on S2. I will probably never understand how Bronica figured to have back detach by simple pressing of dark slide further in, but one just needs to remember that. It seems logical when doing that, one would be wrapping the whole back with his hand at the same time, but there are other ways to press in that dark slide. So, it is quick as hell, but probably too quick at the same time. And the back drops right off, unlike ETR where release button is also simple to use, but back is still hanging onto the camera until tilted up quite a bit. Either one of these however feel great.
On pricing I don't think I agree with any suggestions Bronicas are below other brands (Hassy aside). Perhaps it used to be but I do not see that now. In 67 format I'd never chose GS over Mamiya RB. It must be stated that Europe has far fewer Bronicas to offer than US or Japan and that affects EU market in this sense.