Dark-tweaker, a German site (so the review will be German as well), compared ATI’s Catalyst 3.2; 3.2 modified, Dell’s Catalyst 3.3 and Omegadriver 2.4.07. They looked at performance a Hercules Radeon 9700 pro in various benchmarks.
There is a big gap in performance between ATI’s 3.2 driver versus the Catalyst 3.3 and the Omega driver. Between those last two there isn’t such big difference.
Read the full German review here.