In relation to the difference, I guess the same people who can instantly tell the difference between a current Sony APS-C sensor and a current Canon FF sensor in the final intended use (eg web display, printed image etc) could also easily discern the difference between a 50mp Canon and a medium format image. I assume those people exist? Maybe??
There are probably specialised uses where this is ideal, but personally, I've got doubts about digital medium format. Current post production techniques, pixel shift technology, image stitching and merging remove most of the high MP benefits. Without very wide aperture lenses, you also don't get much of a narrow DOF benefit.
Still, I shoot medium format film cameras and Fuji mirrorless cameras, so I can appreciate that many people just like being different for no valid reason. And when Canon gets into the medium format market, I'm sure it won't take much to convince me that they are the greatest cameras ever.