Your kext is not 8500 but 9700. I am doubt that 8500 is loaded in your case.
Hello, I've been trying some of your drivers with x200 mobility (dev id 5955), I can load the ATILead with Calisto and with 8500 kext. I can get to my desktop and I have two screens on the same screen, I can change my screen resolution (on both screens). Thou I have no QE/CI and I only have 8mb VRam. I just thought I'd tell you. Anything else you want to know?
Look thread about Radeon 200M
If your test the patch report in those thread. About ATILead you got all possible result. What do you say about two monitors? You can use it with different desktops?