Cool stuff.
It's good to stick you toe in the water. I did the same thing with the 1080 on my desktop. Things looked good so I went a little crazy and built two rigs (one with five 1070s and one with four 1070s and a 1080).
I'm a long way from ROI; but I'm in it for the long haul.
Also a big fan of Hive account@bitsbetrippin, they give a lot of great advice for building rigs.