I've had my 640 since November and just installed the thermal blanket. I've noticed since the thermal blanket has been installed my 640 is overshooting the startup temp by 50 - 70 degrees on startup. Also, it takes a considerable amount of time for the temp to decrease closer to my set temp. It doesn't seem to ever hit the set temp, it may get within 10 - 15 degrees high or low.
My software load is U29 and the unit was manufactured in November 2016.
Any feedback would be appreciated.