I have been a long time ATI user having abandoned NVIDIA years ago.  I think I moved to ATI, now AMD, because it would allow a feature in the Madden NFL game that NVIDIA would not plus NVIDIA updates to their drivers in those days were horrendously slow in coming out.  AMD seems to update on a very regular basis.

With the release of Catalyst Version 8.6 one less reboot is now necessary in the day to day maintenance of your computer drivers.

From the release notes for 8.6:

Catalyst Install enhancement – No reboot required after Catalyst upgrade install

This release of Catalystâ„¢ introduces an enhancement to the Catalyst installer. Users are no longer required to reboot their system after Catalyst has finished installing (as long as the installation is an upgrade from a previous Catalyst install).

I for one really like not having to wait for a reboot! How about you?  Does it really matter or what?