Have had most of these, the Fuji 645s are all very good, the AF 645s are fast enough, and lend themselves to what you describe as your chosen style-- they are a bit larger than the manual focus cameras, but all fit in a small bag and do not break your neck to use or carry.
Mamiya 6 should not be expensive at present from what I hear, but it may be more than you need/want right now and slower.
I shot thousands of rolls through a Rolleiflex, and with experience, you can do many things, but the learning curve is going to be different-- maybe your next camera?
The one thing about the folder, is that when wandering about in Paris, it tended to be the one in my pocket, so you were always prepared to shoot a quality MF frame of what ever you encounter.
None should be that expensive in today's market, or contact IgorCamera, these are cameras he often has on his web page-- very old school web page-- reminds me of the old ads in the photo magazines.
He is conservative in his ratings.
John
