I have not used one, but the reason I don't have a propane fueled one is that 1) without a couple of big tanks on site I couldn't run one long enough to get me through some of the one week stretches I have been forced to run off the generators, and 2) Gasoline is readily available from many sources in a SHTF/disaster/storm situation, where Propane is not going to be easily had . Anyone can have a generator, it's keeping it fueled that is the hard part. I have 20 gallons of gasoline in cans I rotate at 1 can a month, then if I had to I could drain gasoline from vehicles, where there is easily another 100 gallons on site for me to use.
I have a 2000 watt inverter that will give me 15 amps steady on about 2 gallons a day, and a 5000 watt generator that burns considerably more fuel. I run the inverter most of the time and fire up the generator to run the well pump and to cook.
I think my next big buy might be a 6500 watt inverter, Naults Windham Honda has a couple of low hour ones for 3900 that were demo units, or they have new ones for 4200.