I just got the 12/500 and was disappointed that the unit gives a warning at 400VA (according to a Kill-A-Watt plugged into the AC before the load). The smart dongle doesn't give any additional detailed information... just a load graphic that shows the load on the edge of the yellow/red. I thought these were spec'd and engineered much more precisely that the cheap China inverters. Guess it should be called a 12/400... Does anyone actually get 500VA out of one of these? should I return it as defective?