When running Warsow at 1920 x 1080, the frame-rates dropped slightly under Gallium3D on the three AMD graphics cards, but the rates remained above well above 30 FPS. The Catalyst driver though was still multiple times faster.
The Mesa / Gallium3D drivers always get slaughtered in the OpenGL Lightsmark lighting benchmark compared to their proprietary brethren. The frame-rates are extremely low and the HD 4830 was 9.21x faster with Catalyst, 17.64x faster on the HD 5830, and 18.77x faster with the Radeon HD 5770.
While the open-source ATI/AMD Linux driver stack is beginning to catch up with the proprietary Catalyst driver on older generations of Radeon hardware as earlier tests have shown, for modern GPUs it will still be a while before anything close to parity is hit. As is shown by today's tests, the Catalyst driver remains multiple times faster than the latest open-source Linux driver stack in their default configurations. At least though this open-source driver is becoming usable for those who simply wish to use a composited desktop with light gaming or video playback and other lightweight tasks.
More results from this comparison (at other resolutions) can be found at OpenBenchmarking.org.