Hi. I'm looking to expand my medium format gear. I shoot mostly B & W landscape, streeet, and portrait. I own a large assortment of 35mm gear and a few fixed lens TLRs which I love to shoot, but with used prices falling as they are I thought this might be a good time to pick up an older 645 system. I'd like to spend less than $300 US for a body, prism, standard lens, and back/insert. Are there large differences between the Bronica and Mamiya systems? Interchangeable film backs is not a huge concern for me. Leaf shutter lenses would be nice for fill flash. Are the lenses comparable? How about durability and ergonomics? I would like mirror lock up and depth-of-field preview. Any thoughts you might have would be greatly appreciated.