Hi Greg - I have the D810a and absolutely love it. I don't need to tell you though that the camera isn't the whole story! But mine at least got the Brian Cox stamp of approval :-)
here's a few through the D810a, using a polarie and lensees from the zeiss 135mm
http://www.astrobin.com/251295/
http://www.astrobin.com/242759/
http://www.astrobin.com/235968/
with the nikon 50mm 1.4 (which I do not recommend for astro).
https://www.flickr.com/photos/photon...or/34124215074
and it does a pretty good job on the back of a Tak FSQ106 too...
http://www.astrobin.com/189475/B/
cheers,
Andrew.