Thanks for the suggestions guys!
I am not new to digital photography, for my commercial work I only shoot digital. Used to own a Hasselblad H5D-40, shot a lot of Phase One, just recently sold my complete A7RII outfit and now I only have my trusty old 5DIII...
What I like about shooting 4x5 is for one the process of really slowing down and thinking a lot about composition and everything else before I expose a sheet. I feel that really helps my photography. I am also not able to achieve those wonderful colors I get from Portra with digital, and I think I am really not that bad in post processing. Lastly, when doing portraits on a view camera, the relationship between the sitter and me becomes more "serious", for a lack of better words, resulting in, although very static, more real portaits than I was ever able to achieve with digital cameras including the hasselblad. That's just how I feel.
I compared 4x5 directly to the sony and the hasselblad, shooting the same scenes. The resolution is not quite there yet with the 40 something MP, but it is enough I guess. The sensor in the sony is great, I almost got colors I liked

(sold it anyways, as this camera is not for me, too small and fiddly, hated the evf and just had to many issues with it)
I also tried the Fuji GFX, not bad, but still, this evf is just not there yet. Maybe with the next sensor generation also the evfs will get better...
I shot a long project about the river which runs through my hometown (see it here:
http://www.martinfriedrich.com/295-kilometers ). I started it with the Hasselblad and used a RRS panorama thingy and stitched. That worked well for landscapes, but as soon as there were bulidings or for example bridges in my pictures I was lost with that approach. Maybe my technique was just not good enough. So back to the 4x5 it was. And did I mention the wonderful colors I am able to get from Portra?

You see, I really like to use rise and fall, I like to work slowly, and that's why I thought the PC-E 45 would be the lens which would help me to keep that style of working.
But I also like my pictures sharp, hate soft corners and too much fringing is just annoying.
I guess I will have to rent the D850/45 and also Otus combo somewhere and see if I can live with it, had the D850 for a short test already and enjoyed the camera more than any other digital camera before.
thanks again and keep your thoughts coming,
martin