I think Mamiya are smart -- smart as a whip.
The writing's been on the walls for DSLRs to have 20+ MPX sensors for awhile. Isn't it interesting how the ZD is priced just a little bit more than the Canon offering? Sure, it's Apples and IBMs -- until you look at your checking account. Guys like me who stagger at $30K for a MFDB system are looking very, very hard at both the ZD and Canon/Nikon, and wondering just how much better my output would be if I did jump up to Phase/Leaf/Hassy/Etc.
At some point in the not too far future, these questions will be moot, because the recording technology will be indistinguishable from perfect replication, and the only thing we'll have to offer our clients is the Moment and the Look -- stuff you can't put in a box.
It's not so comfortable sitting on the fence, sure.