AMDGPU-PRO 17.10 vs. Linux 4.12 + Mesa 17.2-dev Git
On this Polaris 10 system, the latest open-source driver code is a little bit faster than the AMDGPU-PRO driver... Also note that the minimum FPS is much better with the open driver stack at 21 vs. 2 FPS.
At 1080p, the Counter-Strike: Global Offensive performance is very close between these two AMD OpenGL drivers, but at 4K, the open-source RadeonSI Gallium3D driver is doing much better. It will be interesting to see if this changes with the summer roll-out of CS:GO on Source 2.
The fully-open driver stack is also doing much better than AMDGPU-PRO for the Deus Ex: Mankind Divided game. However, it continues to feel like the RadeonSI driver still could be better optimized for this particular Feral Linux game port.