I've used the method described in the OP to install Snow Leopard onto my hackintosh with the following spec:

Mobo: GA-G31M-ES2L
CPU: E5200 2.5GHz
Graphics: 8600GTS (fanless)

I have a dual boot setup with Snow Leopard and Windows 7 both booting fine from Chameleon 2.0-RC3 on the same HDD. I'm using the dsdt.aml and smbios.plist given in the ES2L Kit zip, and have the following extensions installed:
fakesmc.kext
LegacyALC883.kext
NullCPUPowerManagement.kext
OpenHaltRestart.kext
PlatformUUID.kext
Sleepenabler.kext
In addition my com.apple.Boot.plist is set up exactly as suggested in the OP.

The system boots fine but is very unstable. It has never KP'd, but quite often the app I'm using will freeze, then the dock will freeze, followed by the Finder. At this point the system has to be forcibly powered down & restarted.

I had Leopard 10.5.7 installed for a few months before formatting and installing SL yesterday, but I've never experienced this problem before. Any ideas?

Update: I've removed PlatformUUID.kext and Sleepenabler.kext and added -legacy flag to force 32-bit kernel, will see if that helps & report back.
Update2: Switched off HDD sleep in Energy settings, ran chkdsk on the Win7 partition, and repaired permissions in Disk Utility - this seems to have fixed the problem, for now at least.