Have you looked into the OutBack's yet?
OK, I'm no expert but it appears to me that there are "two kinds of pass through". Say, I'm parked next to a friends house and the only "shore" is an extension cord run out the window of his house. If I want to be really sure not to trip a breaker, let's say that I set the "max input current" at 10 Amp. If I start running the microwave or the water heater and pull 12 amps, I think that some "pass through" systems draw the 10 and take 2 (or actually the wattage needed to make 2 amps of 120, plus what's needed for efficency losses) from the battery. I'm pretty sure that what the Outback does is shuts down the input if you mistakenly go above 10 and draws the entire 12 Amps (or the equivalent watts, etc.) from the battery. You can run your batteries down really quickly that way.
I have the Outback and I've kicked the stuffing out of my house batteries a couple of times until I caught on to this. Do other companies' systems do a "real" pass through and minimize the power drawn from the batteries? If so, I'm sorry that I got talked into the Outback.
BH NC USA
PS Brian - Do you understand what I'm asking here? What's your comment on this? Thanks, Bruce