I am owner of the H4D-60 and I compared it to H4X with IQ180 and 645DF with IQ180.
Despite the fact that I got a generous offer to switch to IQ180 I stayed with my Hasselblad system.
The IQ180 is a really good back, but there are there some points I found in comparison:
* The Hasselblad's fuji lenses are much better than the zeiss lenses that were not calculated for digital, they are significantly better than Mamiya lenses and they are slightly better or dead level with Schneider-Kreuznach. With Hasselblad you have the full range from 28mm to 300mm in great quality and even 500mm (300 + 1.7 is excellent).
* 60mpx is sharp until f16 - 80mpx is sharf until f11 due to diffraction - and the difference between f11 and f16 is sometimes important for fuji and Schneider-Kreuznach lenses (it is quite difficult to build/find perfect lenses for this sensors: my 28mm Hasselblad was a selection out of 4! - but it was much, much better than the 28mm Mamiya).
This is not an advantage for Hasselblad but it shows limitation of this high sofisticated systems.
* the focal-plane shutter on the PhaseOne DF caused up to 80% bad results on long lenses (300mm Mamiya) which the Hasselblad system don't have.
* if you photograph moving objects like beauty, portrait, etc: go for the Hasselblad: it's TrueFocus corrects the camera movements after focussing!
* I think the Phocus software of Hasselblad is now ahead of c1. Why? It has all needed functions well integrated and it it much better in recovering of the shadows - but C1 is a bit better in recovering highlights.
* If I have a problem in the interaction of parts (body - back - lenses) I could send it all to Hasselblad (btw I never had a problem with the last 2 systems H3D-50, H4D-60). Nobody will tell me the mis-operation is caused by an other manufacturer.
my 2 cent