A few things I have noticed when using directX 11. Please let me know if these are common or may be from some other issue on my systems.
Good:
-Runs very smoothly with gigantic meshes. Just meshed un-reduced pointcloud data with vertex colors.
-When in directX mode you can run maya very well over RDP without limitation. Very handy when using multiple systems not switching monitors.
Bad:
-Bullet Physics doesn't work.
-OpenSubdiv displacment doesn't work.
-Fluids frequently pop on and off from frame to frame.
There are others I will add as I remember or come accross again.
I was sent a request for answered but this is more of an open question / problem. There is also an issue with nhair and cache with direct x viewport on my machine I haven't nailed down yet. Was hopeing to start discussion on what issues others have found with direct x viewport and what solutions may be.