Tom, prior to the pandemic, I had been meaning to write you regarding your experiences with your Fuji in conjunction with adopted Pentax 645 lenses. I had assumed size wise there wouldn't have been a distinct advantage and weight wise, maybe reduction of a bit of weight....but as you say, giving up a beautiful OVF and AF in the process. I came to the conclusion that it probably wouldn't have been worth it. Just an aside, if I did go with a Fuji body, it would have been the 50R. I still believe that Pentax with their long history of miniaturizing cameras within a given genre (think Pentax MX, ME among many others)...that Pentax might strive for a extremely small (relative) EVF based mirrorless 645 body based on the 50MP sensor. That could then leave the basic 645D/Z OVF body for a future higher MP OVF variant. Initially a Pentax adapter would be made available to use current legacy and/or D-FA/DA lenses in AF mode with the mirrorless body, still resulting in a smaller size and weight system compared to the 645D/Z body. I know highly unlikely but Pentax has been known to surprise users on more than one occasion. Don't get me wrong, I prize the OVF....but for certain traveling situation (ie: cycling or where packing light is a requirement), a small EVF 645 might fit the bill.
Dave (D&A)