AMD Radeon R9 290 On Ubuntu 14.10: RadeonSI Gallium3D vs. Catalyst
Unigine Tropics is running well on the XFX Radeon R9 290 for Linux 3.17+ with Mesa 10.4-devel when compared to fglrx-updates in Ubuntu 14.10, but keep in mind that AMD is soon transitioning to its new unified Linux driver stack and making other competitive Catalyst driver enhancements to try to make AMD graphics more appealing to Linux gamers.
Warsow does surprisingly well with RadeonSI Gallium3D compared to Catalyst where it was at almost 90% the frame-rate.
Xonotic with low image quality settings also does very well when compared to Catalyst.