Simon, I have D800 too.
I like the nikon, but I have some nostalgic feeling about work with MFDB and my Mamiya RZ, I love the slow down and thinking more about the picture.
Nikon is good because in my case, auto focus help a lot, but in future I will like change all to a H4x with IQ 260 or some like that.
This config is very expensive, but I feel that new MFDB delivery more 3D and rich images than DSLR.
Other thing, D800 and C1 is very slow, with aptus files C1 works much more fast and consistent.
I think with new generation IQ/Credo is much much better, not only file size, but flexibility for ajustments.