BFL13, thanks for all the test data. Pretty impressive performance for a $214 inverter. Found a guy online who checked the no-load current on a Prowatt 2000 back in 2012. He read .32a. He mentioned the factory rating was <.80a, which is what it still is. Interesting how both your Powermax no-load reading and this guy's Prowatt no-load reading were both 40% of the factory no-load ratings: 1.5a/.6a (40%) and .80a/.32a (also 40%).
Took a closer look at some pics of the DC terminals on the PowerMax. Agree, the terminal bolts/nuts are located pretty close to the chassis. Not much room for larger terminal lugs.