The FUD starts again.
I assume you are as long as you don't give any examples of this "instability". Yes, catalyst has its error. But with my HD 4670 I had at least no stability issues.
A defualt Linux system without FGLRX = A real stable Linux system .
A default Linux system with FGLRX = Windows ME .
And I'm not joking.
"The game"? Which?
No point in having optimized 3D driver if the driver doesn't even run the game that will utilize it.
(I lost it).
I don't know abput your catalyst but my catalyst 10.7 runs with xorg 1.8 since the first day.
At least that's a REAL problem. For me and many others not using the new 2d acceleration is a working workaround:
Especially when you want to use iceweasel (firefox) you often see black. Even other windows are often with a black boarder.
Some people report it's not working but I think that they just didn't disable it. Happened to me too that I reinstalled catalyst with the config files while xorg running and then the setting was still there on reboot.
In Archlinux it won't take long time.
When you have got a hd 5 card you will definitely not get oss 3d support with a current distro right now.
Besides there are very active people maintaining a repo for the latest development releases of the kernel with drm patches for radeon, mesa and the radeon drivers.
For KDE4, I don't use it, too buggy. From KDE 4.5 I hear no better.
In fact I wonder why people who are actually suffering KDE (I won't call it use) are complaining about bugs in catalyst.