Personally I own both a Mamiya 645 1000s and a Mamiya RB67 Pro S. I'm partial to the RB even though it is heavier it's 1. all mechanical 2. has great macro abilities even without extension tubes. 3. I absolutely adore the 6x7 format. If I'm going out for the day I normally will lug along the RB I have no trouble shooting it handheld down to a 1/60 sec. and I'm 6'4" and 300 lbs so carrying it in a bag doesn't bother me. I picked it up off the bay with 1 pro sd 120 back, 90mm f3.8c lens and waistlevel for $300. My M645 is the camera I take out if I'm strapped for time or plan on hiking/walking a fair distance I find the 80mm f2.8 to be an amazingly sharp lens and having 1/1000 sec. shutter speed is nice though I can't say I've needed it for any action shots yet. I picked that one up with the 80mm f2.8 and unmetered prism at a local camera shop for $180 and I'd rate it 8/10 as far as condition goes. My $300 RB67 on the other hand is absolutely mint. If I had to do it again and could only get one I'd go with the RB there is definitely a wow factor when you look through that waistlevel finder, and the 90mm is a good all around lens which I find to be plenty wide for anything I'm doing.