Conclusion:

Overall the Catalyst 8.5 drivers don't seem like a huge step up in performance. Not that the claims were extraordinary but it's good now and then to take a look at driver performance claims and put them to the test. More importantly in this driver release seems to be a number of new and important additional features such as finally being able to uninstall only video card drivers or motherboard drivers as well as many bug fixes. We had no stability problems at all so don't fear in upgrading to the 8.5 Catalyst drivers if you are an ATI card owner.