You can always buy a different focus screen if you want more brightness.
I compared both systems and bought the Mamiya because I thought the Hasselblad felt cheaper in my hands than the Mamiya which is build like a tank.
I tried the H2 and H3D.
Also the way Hasselblad is working now with closing the system is not a good idea I think, you are buying into a system that will not even let you change for a film back, and I love to sometimes shoot film.
Also the new lenses from Hasselblad are not as good as the old version, while Mamiya is improving lenses today and now.
The main difference with the new Macro for digital is the preparation to send information to the new system and back. Although that is what I heard.
Quality wise I think they would have to do wonders to improve the actual 120mm.
By the way it's rather normal for a macro lens to be MF.
Offcourse I would also love a AF lens but the focusassist system Mamiya uses makes MF a breeze, you don't even have to look a the model, just watch the display
Every system has it's + and - points.
But seeing what Mamiya and Hasselblad are doing RIGHT NOW I'm glad I'm in the Mamiya camp