I've tested a lot of Pascals today with SP_mod#3.
The approach is only 5-7% , according to several different models I have:
1080 FE - 6 cards rig from 330 to 365MH
Palit 1080 GameRock ( Without Premium) - 6 cards rig - from 365 to 384-7MH
Palit 1080 SJS - 6 cards rig - from 370 to 398 MH
Palit 1070 SJS - 6 cards rig - from 288 to 301 MH
So guess I'll be waiting for this 12% gain ...
I only have a 1070 card in my testrig. With the opensource i can reach 275-280mhash with oc. My private kernel oc around 100mhz higher than the opensource so you get an additional 5% from the oc. 305-310mhash stable. I don't have a 1080 card to test