Not sure if this is fact or not but it would seem to me that a propane option would be good from the prospective of the fuel supply not going stale over time if the unit was only utilized infrequently.
The little gasoline generators are great and run well but if they are not utilized at least enough to keep the fuel fresh they do suffer from carburetor and fuel issues which I am thinking will be a huge benefit to going with a propane unit that can be switched to gasoline if you have a continuous use situation.
Just a thought for consideration.
Be well.../B