Many years ago I had a 140mm macro for the RB67—absolutely superb! Other lenses owned at the time (50 and 90) were less impressive. On one occasion I borrowed a Rollei SL66 with its standard 80mm lens for a location shoot at a local takeaway restaurant (using the tilt for front-to-back sharpness over a large platter of seafood). Comparing 11" x 14" Duratrans transparencies from both the SL66 and the RB67, the Rollei prints were clearly superior, with a crispness and micro-contrast not seen with the RB; remembering that the RB negatives were just about twice the area when cropped for the 11" x 14"s, that was quite an accomplishment!
I understand that Mamiya put some effort into improving lenses for the RZ, particularly the [previously] dodgy 50. And I still use M645 lenses with an Aptus back—some of them are excellent.