Interesting that the clockspeed difference might explain the advantage that 970 has.
How about the vram usage of amd and nvidia cards in other games?
Usually my 970@1.5Ghz is faster by about 50-60% than my 7950@1.1Ghz. The clock difference is 36% so the rest must be from architectural improvements of maxwell.
Actually the clock speed itself is an architectural improvement or just an architectural difference, since Nvidia is using quite higher clock speeds for a while now.
Still we are talking about a Tahiti chip. I am sure a Hawai chip at 1.1Ghz would be just as fast as a small Maxwell.
Now regarding the vram, the 970 does have the tendency to use a bit more vram. Always according to MSI Afterburner.
Taking data from my latest benchmark videos, in the Infiltrator demo, the 7950 used 1.5GBs, the 970 1.9GBs.
In mad max the 7950 used 900MBs, the 970 1.25GBs.
In rocket league, 7950 used 500MBs, the 970 730MBs.
In battlefield hardline, 7950 used 1.7GBs, the 970 2GBs.
In ashes of singularity DX11 7950 used 1.25GBs, the 970 2.5GBs (dafuq didn't notice that before)