Mesa 20.3 + Linux 5.9 Is In Great Shape Against AMDVLK, AMDGPU-PRO
Shadow of the Tomb Raider ran into Vega 56 issues with AMDVLK. Aside from that issue, the Mesa 20.3-devel performance tended to be just behind the official AMD Vulkan drivers for the Radeon RX 5700 XT and Radeon VII.
Thrones of Britannia was seeing slightly better performance on the AMDVLK/AMDGPU-PRO driver options.