I am currently testing vPro with SCS installed on my non-vPro desktop and a single Latitude E6530 as my vPro machine.
The AMT event log shows a "operating system lockup or power interrupt' about every 2 or 3 minutes while windows is running. According to my tests, this only happens while windows is booted, not under a linux live cd.
I'm not sure what kind of lockup is meant, but since it says 'or power interrupt' I think it should be critical enough to be noticeable during usage of the pc.