I've tweaked my KAB-4 till I'm blue in the face and have to say I'm underwhelmed. I'm lucky to get two batches out of a tank of propane. I knew it'd eat the stuff compared to my little turkey fryer unit, but thought the speed of heating would compensate a bit, no so in my case.
I have to open the vent fully to get a decent even, blue flame, but doesn't seem to be significantly faster to boil that my little 65k btu (10psi) unit.
For safety and efficiency's sake, I will eventually go electric but would love to have the banjo burner at least meet my expectations.