Glen, I wouldn't take too much stock in what those over the big pond are doing. Our skies are better
(when it isn't raining!)
Maybe it's a good time to re-read Ray's thread on exposing past the read noise? While the read noise is low with the 1600, it's not zero. You'll want to expose your background beyond the total noise in your subs, for best results.
Personally, I'd be looking at one of these as a less expensive, large, cooled sensor for conventional DSO imaging. In which case, I'd only be interested in using unity gain FWIW.