Just wanted to say this thing is pretty nifty: a significant improvement over the AC2 (and of course AC1) but probably not enough of a difference to warrant replacing the AC2 if you already have one. Of all the new features, the silly one I like most is how the new battery backup works: internal Li Ion versus 9V alkalines This gives me peace of mind. I'm going to install the alarm module soon so that it screams if my temperature deviates beyond tolerances. I'm determined to have no more death by temperature issues!