Playing fullscreen in non-standard resolutions

In the DirectX9 client it is possible for me to play in fullscreen at 5760x1080. This feature is not present in the DirectX11 client. The reason this is important to me is that I run an AMD Crossfire setup which can only fully function in fullscreen mode. When playing in DX11 the only way to achieve my desired resolution is to play borderless windowed. I would love to use the new features of the DX11 client, as well as get away from the issues DX9 seems to have with AMD GPUs.

I realize I am in a minority, but I really feel like the DX11 client should not be missing features that were present in DX9.

I also realize this is a case of first world problems. But I'm not angry, I just want SE to know that at least a small part of the playerbase wants this feature carried over.