I've had my SQs for many years (almost fifteen for my oldest) and the only problems I have had are with the backs and leaking light seals, which is a fairly easy fix and is the one weakness of the Bronica. The glass is excellent.

Pay attention to the battery. I learned recently that the battery check light can be fine but still lack enough charge to properly time the shutter. Mine was periodically missing the set shutter speed. New battery, no problem.