Graham, I have both cameras.... I use the Bronica more as the vertical format seems to fit more applications that I'm in (people shots). I don't tend to print over 8X10 very often anymore and there is an almost imperceptible difference at that enlargement size between the cameras. While not cheap feeling, the Mamiya isn't as tactiley gratifying as the very solid feeling Bronica. When I added the Mamiya a few years back, I did some side by side comparisons and determined that the optics were comparable but at 11x14 and up, the format advantage can be seen with the Mamiya. The Mamiya is certainly a more complete system to buy into and grow with, especially in wider focal lengths but the 45mm on the Bronica has served me well and I don't yearn for another wide angle as it covers my duties nicely.
A couple of years ago, I got pressed into a wedding as a last minute emergency. I used the two systems that day and the couple's 8x10 album would have anyone guessing at which shots came from which camera. If your duties mirror mine in some way, I'd say to be happy with what you own but if you tend toward larger prints and projects, the Mamiya would give some performance advantage. Also, consider the format orientation for your intended use... I wouldn't have thought about that aspect if I didn't have both and keep reaching for the Bronica for my duties, many times based upon that detail alone. If you tend toward field/landscape applications, this would likely be the opposite for you. I had some knee surgery about 4 years ago and am only now returning to some hiking capabilities. I would be taking the Mamiya stuff for that and the Bronica would stay home, for instance.
