Interesting move from Laowa; I've been pondering over the last few months whether they'd pull something out of their hat exactly like this. I would have suggested that Pentax see if they can license the lens, strip off the shift mechanism and turn it into an inexpensive fully manual wide-angle lens for the 645 system. The sharpness looks okay for the borders of the 44x33 sensor. Maybe the Pentax lens coatings would help the lens flare as well; although looking at the DPR Review video, the lens is marked as "Sample" and reading the
Phillip Reeve review he makes the comment that the production lens should have further "blackening of the lens elements" to help with ghosting.
That all depends on where the rear element in the lens sits; it may not have the room to do so without entending into the mirror box too far. Would be nice for the 645Z/D users to get a wide angle option again.