And as you can see, where extra resolution exists, it will be utilised. The 645z handily beats the Nikon D810 and Sony A7r where fine picture elements -- such as feathers -- exist, but falls way behind the detail offered by the larger-sensor / higher megapixel Phase One IQ180 and Phase One/Mamiya back.
Of course, this is a cherry-picked example; samples such as cards, and printed faces showed only minor differences. Some, very little at all. But where differences exist, they always favour the higher resolution sensor- sometimes by huge steps.