I'm interested in these answers too.  My single is Rev E (shipped Aug 22) and came with 872 firmware.  Which was odd because it would throttle almost immediately.  I took the case off and got it stable with 832 firmware.  Watching the temperature in CGminer (often cycles up & down), I've not seen it go above 48.2C so I figure that must be about the throttle-temp-trigger.  However, if I load the 864 firmware and watch the temps, it appears that anything above 45C will trigger the throttle.

I should take the heatsink off and apply that Artic Cooling paste to see if that'll lower it any.