The "ati" driver is just a wrapper around radeon and other drivers.
I assume you're talking about changing OSes here ?
If so, the main issue is that we need to either figure out settings that will keep Compiz from stepping on the video window or make changes somewhere in the plumbing so that this happens automatically. It's not really a driver issue AFAIK but it is something we will probably have to work on anyways.
I can't seem to find the radeon driver using the same git url as the ati and radeonhd. Id' love to try it. If you, or someone... can post the RADEON git url I'll compile up a copy and see how it works. A url that I think should have been in the announcement article on Feb 24th, or at least a link to a page containing a brief "here's how to try the driver" (hint, hint).
This is the URL I already downloaded and compiled:
and there is no source at:
So, unless the freedesktop radeon driver is named radeonHD (Huh?)...and someone is deliberately trying to confuse us all...