I have a GTX 770 and never find a need to change my settings away from the stock ultra high. People's tolerance for occasional FPS hits on some views varies but I can only imagine how much better it would be on a gtx1080.
The 1080 is great. I can usually get by on stock ultra high and a sunrise or sunset round (long shadows) and holding in the mid to upper 50's at the lowest. But some courses will cause that to dip to unacceptable levels here and there.
I'm looking forward to Unity 5.4 to see if performance improves significantly. Then we can add 3D grass and proper waterrelfextions to bring it back down to where we are today!!