I use my ETRS mostly for street shooting, it's my favorite portable. I love using my 150mm lens for general use. Perhaps getting use to street shooting an RB67 may have helped develope good hand held techniques.
In all honesty, both the Mamiya n the Bronica 645s are wonderfull cameras as far as portablility n hand held MF cameras go. It's a nice in between overlooked format that yeilds amazingly sharp images.