You already mentioned output de-rating and long term storage advantage.
90-100lb LPG tanks are easily moved with a hand truck, responsible transport and storage must be considered. Realize that exchange 20lb cylinders (really, 16lb due to 80% fill) are not always full.
Dangerous emissions are much lower with propane, no problems working in say a vented garage during a hurricane.
Oil changes show the much cleaner burning fuel - oil is darker but still clear. My brother's FIL managed a Honda powersports store for 12yrs. He says the worst things people do with small generators is neglect oil change schedule. It helps to put a small fan on the engine for cooling.
The only thing I don't like is the external mounting of the regulator. Not the greatest if you're throwing it in the back of the truck all the time without protecting that.
My brother has a Honda 6k he converted to tri-fuel. He uses propane is a backup option only, has a few 90lb tanks. He doesn't keep bulk gasoline beyond yard machine needs unless a hurricane or hard frost is due for SE TX.