I'd have zero interest in a what is now misleadingly called a "medium format camera". In fact, I'd have less than zero interest and instead be annoyed that the manufacturer was wasting time on a camera incorporating a sensor that just isn't all that much larger than a full frame sensor.
Back in the film days, "medium format" was typically 6x6 or 6x7. I had a Mamiya C33 TLR that used 120 or 220 film. The frame size was ~ 60mm x 60mm, or 3600 sq.mm.
Doing the math, a full frame sensor is ~ 36mm x 24mm = 864 sq.mm. A "real" medium format 6x6 had > 4x more surface area.
Now ... the Pentax 645 series gets it's model name because it can use the old 645 lenses. However, the Sony "medium format" sensor is actually 44mm x 33mm = 1452 sq.mm.
So, it really isn't that much of an increase in sensor size to go from f.f. to m.f. My impression is that you have to at least double the sensor area to see a real, dramatic difference. Instead, you pay a LOT of $$$ for less than 70% increase.
That's about equivalent of going from m43 (225 sq.mm) to Nikon APS-C (368 sq.mm) = +64%
However, man EF lenses might have some "extra coverage" of the m.f. image circle, with edge softness and significant vignetting.
No thanks.