Yea, I noticed something similar. When testing UT2004, the general thing that impacted the performance of r600g was texture size. LOD is important, but way after texture size - the optimal settings that I've found for my cards was pretty much "low" texture size and "high" LOD.
Does it make sense to use high LOD with low textures? I mean, the textures are already low-res, why store even lower res variants?