I did most of my riding with heavily laden saddlebags. The bags all wore on the back where they rubbed against the brake, cable bridge, QR, etc.
Had I had the sense to turn my brakes around, that wouldn't have happened.
BTW. The rear brake on my off topic Maruishi Mountain/commuter bike has the rear brake mounted under the chainstays ... it works great.
Amir Avitzur
R"G Israel