The Radeon Gallium3D driver also did not have any stability or artifact problems. Both the "R300g" and "R600g" class drivers were tested, which span hardware coverage from the oldest PCI Express pre-X1000 graphics cards through the latest Radeon HD 6000 series and Fusion. The graphics cards that were tested under Doom 3 on Mesa 7.12-devel / Linux 3.2 include the Radeon X800XL, Radeon X1950PRO, Radeon HD 3850, Radeon HD 4550, Radeon HD 4650, Radeon HD 4770, Radeon HD 4850, Radeon HD 5750, and Radeon HD 6450. This is just a small selection of my ATI/AMD hardware, but you can compare them to The Most Comprehensive AMD Radeon Linux Graphics Comparison.
Like the Intel and Nouveau drivers, the image quality settings had little effect on the actual image quality or performance. When running Doom 3 at 800 x 600 at Ultra, the good shape of the open-source Radeon stack is clearly visible. Any of the tested Radeon graphics cards spanning six generations of graphics processors handled the id Tech 4 engine without sweating, albeit the visual details are not as mighty as with the binary driver. Even the Radeon X800XL began these tests pushing out over 60 FPS. At around 85 FPS is where the graphics cards were hitting a CPU bottleneck within the Radeon driver (using the binary drivers with these cards there's no issues shooting much higher).