I've had issues (both sharpness and loading onto reels) in a Hasselblad back that had film in it for several months, as well as a Mamiya 645Pro back. So I'm now careful to take an extra shot if the film has been sitting for a while in the Hasselblad. Never had an issue in Mamiya 7. From that I draw the conclusion that it's the cameras the bend the film backwards from the way the roll does it that's an issue.