If somebody cares about Coh2 performance it's better to look at Coh2 benchmarks:
http://www.anandtech.com/bench/GPU14/857
Different architectures suit different engines, and it'd be a mistake to extrapolate UE3 performance (for example) and expect the same results in Coh2. The performance difference is big enough that you're actually getting better power efficiency from AMD's 3 year old GCN architecture than you are with NV's 770/780.
Coh2 is probably still in the minority, but it's worth keeping in mind.
(Oh and 970/980 does extremely well as seen in the higher res benchmarks)