I've had the RB for over two years and I must say that grip is nearly indestructible!! You will have no problems with that at all. I packed the RB around like a suitcase, holding it by the grip...and felt perfectly safe in doing so. At least in 6x7, Mamiya did not make anything weak or flimsy. I've since moved on to large format, but the Mamiya and ALL its acccessories was the toughest camera system I have ever owned. Built to last.
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"Shooting digital is about as creative as turning on the radio......."