Here are some thoughts that may or may not help you sort through your decision. Not sure what the SE has over the Mamiya presses. OK, I use a Graflex XL, but it is kind of a similar style of camera to the Polaroid 600SE and Mamiya Press. I just like the versatility of these press cameras though I think the XL kind of scares some people. Every exposure requires you to remove lens cap, dark-slide, set shutter/aperture, focus, compose, shoot and wind-on. Not the easiest set-up but I kind of like that involvement even though it takes practice, practice, practice to make it all second nature so you don't goof up. Did I mention that I wished it fit in my pocket? Sure do, but this is med-format film we're talking about here. But here is what you get for the hassle. Compared to the Mamiya 7 you loose the quick handling but gain faster lenses (some f/2.8, not sure what the SE has) interchangeable film backs, closer focus and macro capability plus multiple formats and polaroid capability and affordability. Compared to the RZ you gain the faster lenses, portability and hand hold-ability for low light. Similar with the 500 plus multi-format backs and affordability again. I can't think of another way to get 6x9 and instant film in a rangefinder package.