Between Catalyst 8.3 and Catalyst 8.10 there is a regression within AMD's own binary driver. However, even with the regressed performance, the Mobility Radeon X300 is still faster on the old binary drivers than with the modern open-source Radeon Gallium3D stack.
When running the ioquake3-based OpenArena game, which is much lighter than the earlier OpenGL tests, the open-source RV370 performance at present is still horrific in contrast to four-year-old binary blobs. Catalyst 9.3 from March of 2009 was nearly five times faster than the latest Linux 3.2 / Mesa 8.0 open-source Radeon support.
When running OpenArena at 800 x 600 rather than 1400 x 1050, the Catalyst 9.3 was only 2.7x faster.