The improvments in image quality is just the tweaking of the default Performance/Quality settings, other then that there are no image quality things.
But he does sometimes replace one file with an older version, if the newer version shows stability problems, etc.
He doesnt actually rework the drivers, as that illegal and why nVidia tried to sue him (they thought he was reworking the drivers, but after he proved to them he wasnt, they tried to have the last laugh and made him take their logo off his site....lol)
But yes, he is on ATi's beta team, and a lot of what he does is now done in the official drivers anyways, and so the main benefit of the Omega drivers is the software suite that comes along with them.