I found that between my DSLR and my Hasselblad, I really don't need a 35mm camera.
Re #3. These may have existed but were in no catalog or literature that I ever found, and I amassed a lot of data on the entire Bronica series.
The two most important? The weight and the weight! :D
My wife and I carried an RB and lenses all over the place on hikes at one time. No more.
I should also mention that the Bronica takes 2x more photos per roll, which gives me a lot of shots per shoot with that less weight.
If you regularly shoot ISO400 on your 6x7, you'll probably find that you get the same quality from ISO100 on 645. But then, it's pretty damn hard to beat Acros or TMX in 6x7...
I think there are other variables to be considered. I have and use the RB67, a Mamiya 645, a Fuji GS645, and the Mamiya TLR system. Prior to owning the RB, I used a Kowa 6.
The RB is my "serious" camera. Always on a tripod, and with interchangeable backs, I use it much like others use sheet film. (other than the individual sheet development). Second, though, is the Fuji. Usually used handheld, it yields negatives very comparable in most prints from the RB. It just has a different "look". However, I'll take the Fuji places I won't bother with the RB.
They are all tools, and you have to use the one that's comfortable for you to use and meets your needs. Size, weight, lens selection (or not - see: Fuji) and shooting style all figure in.
A carefully exposed and processed negative from 645 can be beautiful. In fact, I am having good enough luck with T-grain films in 645, I've started to shoot some in 35mm just "to see"! YMMV :cool: