As a result of a discussion on the Photozone camera forum, I tried the CZ85 on both the NEX-5n and the 7. it turns out that the 7 is not only problematic with symetrical designs that have a short focal length, but also at longer focal lengths with a wide aperture.
On the NEX-5n the CZ85 is close to perfect (at 1.4). Sharp from corner to corner. It is getting even better when you stop down a bit, also because there is a lot of LoCA wide open, but it looks very impressive. With the NEX-7 there is a clear bending of the focal plane in the extreme corners and even when focused in the extreme corners, there is less detail than with the 5N.
At say f2.8-f4 the effect is mostly gone.
In practice I do not think it is very important, when I use de CZ85 close to open, it is on 3d subjects with little light. The extreme corners are usualy not important in that case. Still, there is something strange with this sensor.