Pretty good! I get the occasional crash, usually when running melodyne or a bunch of instances of Slate VCC. usually a reboot takes care of anythihg. I am working, still, one crash is toomany when i have sessions all day. customers haven't said anythihg to me about stability becuase I recover quick if there is a freeze. By the time they get back from runnning to the bathroom I have things back up and runnning.
I am pretty sure any issues with system load will be dealt with in 64 bit version...I hope!!!