That's a tough call. Mamiya lenses for the RB and RZ cameras are right up there in quality with the best of them, so I don't see that as a real concern. Even the ones that are supposed to be dogs are better than good. I seriously doubt that lens quality would be an issue. Hasselblad prices have fallen a lot in recent years, but the cameras and lenses still command more than the equivalent Mamiya RB/RZ series gear. There's no doubt that the Mamiya cameras are bigger and heavier, but they are also more versatile. Closeup work is a snap because of the bellows focusing. There's no need for expensive additional accessories to do macro work if that's your thing. The same types of finders are available for both systems, so it's a draw there. The biggest advantage I see favoring the Mamiya system is the larger 6x7 negative that requires very little cropping to fit the standard paper sizes. The square negative, on the other hand, requires that you discard a lot of the negative's real estate to fit the rectangular format. Printing square for a 6x7 negative, by comparison, requires that you discard very little of the negative's real estate. The choice is up to you, of course, but I'd consider a trade if I could get a good body, a finder, a couple of backs, and at least two lenses for the Mamiya system in trade for your Hasselblad gear.