It could be quite good as after all its full frame. An 11002 chipped astro cam starts at about US$5000 so...
Here is a shot I took a couple of years ago 2 x 60 minutes Nikon D800e with 14-24mm lens at F2.8 ISO400 (it also has some narrowband material added from my FLI Proline camera but the guts of the image is the Nikon).
http://www.pbase.com/gregbradley/image/152348475/large
36mp full frame in telescope shots is probably not ideal. STL 11 is only 11mp full frame so Sony A7s modded and cooled at 12mp large pixels with deep wells should be better. D800e wells though are quite deep. From memory they are about 45,000 electrons which is pretty decent. 36mp would probably suit a widefield telescope like an FSQ106ED or similar.
But at $4000 there are a number of astro cams it would compete with. The APSc Canon astro DSLRs were much cheaper and thus a viable alternative to dedicated astro CCD cameras.
Greg.