AMDGPU vs. Radeon DRM With Linux 4.14 On GCN 1.0/SI GPUs
Also no real difference with Metro: Last Light Redux.
Tesseract does benefit from AMDGPU over Radeon.
Unigine Superposition didn't see any real change in performance.
Xonotic had only a very small gain if any from using the AMDGPU DRM.