[Brightcolours]

Dave, there's more than IQ (in terms of resolution and other parameters to measure). If you go larger than FF, not depending on MP-count, you get necessarily longer focal lengths. These change the proportions of in focus / out of focus parts in a picture. Wether that's to my taste or not, the curse of larger than FF formats is shallower DoF - and the best pictures of these cameras not only convince by the amount of detail but also by isolating the subject much more than fast FF lenses can.

 

I had better bokeh with a 110/2.8 in front of the Mamiya 645 than I had with a Zeiss 85/1.4 in front of a Contax/Yashica. Not to mention the difficulties in focussing very fast lenses with only a matte screen in a comparatively tiny finder.

The longer focal length being equivalent to the shorter focal length on FF, there are no changed proportions at all, actually.

 

The issue with the current "affordable" MF is that it is to film MF what MFT is it FF: a lot smaller imaging size. It does not even approach the smallest of medium format size (645). Because of the small MF sensors used, you can't get shallower DOF with the lenses on offer. 

With a crop factor (compared to 135 format) of 0.79x, the 110mm f2 is a 87mm f1.6 FF equivalent. 

 

Of course, it is fine to prefer a certain lens over another, and very understandable that one has preferences for certain lenses.I for instance prefer how the Tamron 85mm f1.8 VC USD renders over how the Nikkor AF-S 85mm f1.8 renders.

 

What I do not like about the design decisions of Fuji: the bigger sensor does not bring a possible more shallow DOF because of the lens line up. The mirrorless advantage of size and weight seems lost, Hasselblad seems to have gotten that right with their latest. And it is not a pretty camera to look at.