On a 970 here and get better average FPS using DX11 too.
For your follow up questions, the heavy batches FPS is slightly higher with DX12 so in theory your minimum framerates in game should be better than with DX11. However it is a tiny difference so doesn't really effect my decision making.
It was said that DX12 would get a few extra bells and whistles, perhaps better lighting but you'd have to play test that yourself. I don't know if it would be true in the benchmark as surely that should compare like for like.
Steam overlay etc. also works with DX11 and not DX12 at the moment so to be honest for now I don't see a strong reason to use DX12 for Nvidia users like us. Nvidia graphics cards in the future are likely to gain from it, so in some senses you could see it as a future proofing of the engine, especially as they build on it in the future. And AMD owners are of course enjoying some benefits from it now, which is good for them.
