The main reason for going P1 these days is the full frame sensors, leaf shutter lenses, Capture One integration, the advanced capabilities of the backs (frame averaging,..) when combined with the XF body (focus stacking) and the Schneider lenses that are very sharp across the frame of a full frame MF sensor.
In my view they are way oversized and overpriced for small MF sensors such as the one used in the 50mp backs.
The cheapest way to get such a sensor and matching lenses is the Fuji G system.
The Hassy X system has better lenses with leaf shutter lenses, but they are much more expensive. And in terms of body capabilities the Fuji is significantly ahead. Especially if you can afford the GFX100s.