OpenSUSE 11.4's kernel doesn't have FOSS Radeon support for Llano, so that rules out my Llano desktop and laptop for any meaningful testing. Being that my PhenomII/HD4650 system isn't hooked up right now, I opted to test my wife's Athlon II/HD4200 laptop.
The laptop is still running an old Ubuntu 10.04 installation with the initial FOSS 3d support, and runs Compiz admirably, with every effect enabled, wobbly windows, exploding windows, paper-airplane windows, desktop cylinder, etc... All running smoothly on a 2 y/o IGP and a 2 y/o operating system.
1. Booted up OpenSUSE, everything seems to be going OK.
2. I open a few random applications, and move around to different virtual desktops. It seems pretty smooth, much better than previous KDE experiences.
3. I attempt to go all-out and turn on more desktop effects. I get a message saying that everything I tried to turn on can't be turned on, and also numerous effects that were already supposed to be on by default can't be turned on.
All in all, it was a huge improvement in speed, and although it could barely do any desktop effects, it didn't actually crash or show any screen corruption during the brief time I tested it.
However, the fact that most of the desktop effects can't be turned on doesn't instill confidence, nor does it make me want to recommend it for people with AMD hardware.