I have a LOT of hours on my Champion 9k dual fuel. Bought it from Costco (apparently it was a Costco only model).
Has 240v. Has "automatic voltage regulation" which means it runs over-voltage and has a regulator. Very smooth/clean power, especially for a non-inverter. My next sized down generator is a standard generator and has very dirty power. Motors (such as fridge compressors, etc.) sound like crap when running on it. Lights have a flicker. I hate that thing (Brute brand; Briggs engine).
I have a whole-house interlock kit setup. Have used it during outages.
My longest run is 6 weeks. Yes, 6 weeks, and much of that running 24 hours per day, changing oil every other day. Construction reasons, but it was our primary power source (had a smaller generator for at night if loads were to be low). I had one issue where the float for the carburetor wore through. Champion sent me a whole new carburetor, plus some other parts just for kicks, all for free after I told them how many hours were on it.
Now, the main power button seems to not turn off, not sure why, but it drains the battery slowly leaving the electronics on. Still runs fine though, and I haven't looked into fixing it as I've just been pull starting it this year. Since the battery was drained, it now needs replacement for electric start. Standard small motorcycle battery, and I've had this thing for something like 6 years, so it was due anyway.