It technically really depends of your rig. Most of the time, for ROTR, you're losing a bit of framerate if you're running Nvidia. Not much really, but globally it's useless.
DX12 talks is currently overblown. It's, mostly, encouraged by AMD followers because of the huge gap there is in Drivers between Nvidia and AMD, on top of the fact that AMD has basically invested a lot of their architecture into mantle, and what it means for DX12/Vulkan (Async Compute/GCN).
However, the big issue with DX12/Vulkan is that you're putting in the hands of the developers what you use to put in the hands of your GPU manufacturer / driver. Sure, theoretically, reducing the driver is a good thing, if you have extremely good developers, and a fixed architecture. If you don't, and PC doesn't have it, then it's a whole different story. If you're dealing with a very good developer, capable of using the capacity of your GPU at its best, then yes, DX12 may well bring you more than DX11. If you don't, then DX11 might well give you more than DX12.
So well, I'd rather have them focusing their energy on doing, something else, like better assets, improved lighting technology, than remaking their whole engine for DX12 or Vulkan for that matter.