With the IQ250 I think the issue is the proximity of the of sensor to the rear element of the lens in use with a tech camera, in that the close the rear element is to the sensor, the more issues with color sat loss on movements will occur.
I can provide a bit of feedback, from tech camera lens standpoint. I recently was able to test the Arca M2, setup for a DSLR mount, sold as the DSLR2. With this setup, you can mount a Sony A7r and use almost all of the current lenses from the tech lineup, exceptions, (23 Rod, 28 Rod). The wider the lens, the closer it has to come to the sensor, so I expected good results with the 60XL and 90mm Rodenstock and OK results with the 40mm Rod and 35XL.
I realize the A7r is not the same size, or MP as the Sony sensor in the MF cameras now on the market, however I believe the Sony 35mm sensor and the MF cousin have similar characteristics. The Sony 50MP sensor in the various MF cameras out there, Phase, Hasselblad, Pentax is the same base sensor, and it uses micro lenses. Extreme shifts on these types of sensors, does seem to have issues. I don't know if the individual pixels on the 35mm Sony are larger or smaller than the pixels on the 50MP version, it's my thought that they would be larger.
What you are going to see with shifts up to 10mm, is excellent to good results, dependent on scene. As you approach 10mm, you are going to start seeing more color/sat fall off, no loss of details. On shifts up to 15mm you start to see significant color/sat fall off, as much as I feel 40% maybe even 50% depending on the lens used. Past 15mm and things really fall apart. You hit the edge of the sensor by around 18mm anyway, so pushing to 20mm was moot.
Of the lenses I used, I found the following: LCC's were shot with each.
35XL, excellent on center, good to 5mm shift, OK to 8mm of shift, very harsh color loss past 8mm and strong magenta cast.
40mm Rod, excellent on center, good to 10mm shift, Very harsh color/sat loss by 15mm
60XL excellent on center, very good to 10mm, good to 15mm, useable at 18mm but some work required on color recovery. CF was used on 60XL
90mm Rod, excellent all the way to 18mm.
You can assume the 50MP CMOS in the Phase IQ250, will have similar results with tech lenses. Maybe a bit better but the loss of color/sat on shifts of 12mm or more is pretty considerable. The 32mm Rod may do a bit better, but when you look at the total cost of that lens I can't see the justification if you are going to be limited to 12mm or so of shift.
Is recovery possible with LCC?
Yes and No.
Yes, in that I found most times in C1, I could recover the loss of green saturation and hue on extreme shifts, not perfectly, but enough that I could make a print.
No, in that a blue sky is very hard to balance out as the loss of blue hue/ color shifts is the hardest to recover. This is especially true if the sky is pure blue with no clouds to help break it up.
The amount of time in post to recover the files to me was extreme mainly due to the color/sat loss on shifts.
What Gerald is seeing with his IQ250 and the TS-E lenses is totally different as with these lenses, the lens is farther back from the sensor (as I understand the setup), thus the color sat loss issues will be much less extreme to none. The 24 and 17 TS-E's are designed to work with a mirror box which should allow the lens to be much further from the sensor at infinity.
Just how close you have to come with the 35XL is around a 1/8" gap, and the 40mm Rod is around 1/4". The 60XL allows for a much healthy gap, approaching around 1/2".
Paul