I have one. Used it this weekend to power our camper. Gas doesn't last as long as the propane but has a higher amperage output. The propane is handy but costs more. 1.6gal gas tank gets you 7.5-8.5hrs at 1/4 load. Can't remember exact hours. Propane gets something like 12-14hrs at 1/4 load. What I found was either one will run out at the least opportune time. lol
Mine is a Champion dual fuel inverter model. Something like 3400-3500 watts. I believe I had around $1250-1300 delivered. You may find them cheaper now since they've been out a bit. I did have a couple issues out of the box. Thing wouldn't start. Tech support walked thru a bunch of things and ended up telling me to shoot starting fluid in there. Wasn't real keen on starting fluid in a brand new generator but that is all it took. I'll be contacting them again soon. It doesn't shut off when you turn it off. If running on gas you have to choke it to kill it. On propane you simply shut the valve off and it dies fairly quickly.
I mostly only run the generator in the summer. Not alot of need to run it in the winter unless I am using tools for something. I will soon have 2 -40# tanks hooked up to my propane so it would last a long time. You are correct that no matter what you always run out of fuel at the least opportune time.
Knock on wood my Champion generator has given me really good service. I have owned it for 2 years and have had zero issues with it. We built the entire cabin with it and when we had the camper I ran an AC unit on it. I have put alot of hours on it and alot of them have been running near full load. I was surprised at only 2000 watts that it would run my table saw and stuff but it did. Occasionally it would kick out when you bound the saw up, but it really wasn't much of an issue.
Not really looking to replace by genny yet, but I have noticed seeing more LP portable generators and the price has been coming down. OF course I think from doing the math the LP is more expensive per hr to run. Not really an issue for the amount that I would use though. Honestly in the winter time I seldom take the generator with me to camp unless I need to run tools. With having solar for lights and pump and then having both a wood stove and propane stove that don't require electric there really isn't a need. The only thing I really need the genny for is to run the fans and if I ever install a window AC unit in the summer. I may drill a well one of these days too and would need a genny to pump out of the well. I will probably get a remote start when I update too. That would be handy at times.
