The difference between DX11 and DX12 between AMD and NVIDIA is quite noticeable. But for DX12 we will have to see big titles as well, because they only benchmarked Ashes of Singularity yet. we still dont't have many titles, in order to come to final results. but overall AMD showed a Positive DX12 hardware perform at a better rate. While NVIDIA will have to work out on Software to gain the enhanced Benefit of DX12.
Well, 970 and other high End NVidia GPU still performing good, future proof of another 2 years, if NVIDIA retain their support for maxwell. Because what they did to kepler series we all can see. at 1080p 970 is still bang for bucks in that price range.