Two new wide angle lenses and the D800 is a new camera

Field curvature is a problem on all WA lenses. However they also have quite a lot of DOF, so AF will often focus long before it reaches infinity and the edges look blurred.

I have been experimenting with my 16-35 F4 zoom, and found that using MF and altering the focus made a big difference to the edge-to edge performance. A lens I was struggling with (and thought may even be defective) turns out to be very good once you understand it.

Very interested in the Samyang as well - any idea how much effective view angle you lose on correction? Looks moderate in your example.