Get Hasselblad X1D-50C at B&H Photo.
I discussed the Hasselblad X1D-50C sensor in some detail several days ago, but I had not shown a diagram of the differences, and I think that tells at least as good a story as the cut-and-dried numbers—see below.
Aspect ratio is a consideration for some photographers. In particular, cropping the 3:2 aspect ratio of a 35mm full frame camera to 4:3 yields a 32 X 24mm sensor area.
If the intent is to shoot 4:3 aspect ratio, then the real difference in imaging area is 43.8 X 32.9 vs 32 X 24 mm. The sensor area at 4:3 is thus 88% larger with the X1D sensor. That is a big gain.
For perspective, 35mm full frame is 2.3X larger in area than APS-C.
On the flip side, if one prefers the 3:2 aspect ratio then the sensor size difference becomes a more modest 43.9 X 29.3 mm for the X1D, a 49% area advantage in sensor area [43.9 X 29.3 / 36 / 24 = 1.49].
Could it be the year of big sensors? If the Fujifilm rumors are true, and Ricoh/Pentax gets rolling, it could be an exciting move forward in mirrorless larger format sensors. The good news from my point of view is that if Fujifilm offers a large sensor mirrorless, it is not likely to use X-Trans sensor, thus sidestepping all the artifacting unpleasantness.
Note that the X1D has no wide angle lenses at its debut, which is a severe constraint, at least for stuff I like to shoot (I don’t count ~35mm as a wide angle, but as a mildly wide normal). Note also that the choice of a 4:3 aspect ratio reduces the size and weight of lenses. Leica S with its 3:2 aspect ratio is the oddball; larger formats are almost all likely to go with 4:3 sensors—easier for lenses and that is the ratio that Sony commonly makes—a cost issue.
Regardless, it is now my conviction that every camera ought to have SuperRes pixel shift mode as per the Pentax K1, as that capability dominates the quality aspect, albeit with the restriction of tripod-only and no subject motion.