I have a built in Onan 5500 EVAP. It is just shy of 7 years old. I run only non-ethanol gas in it, StaBil Marine formula in every gallon to goes through it, I run it for 1 hour the first of every month, and NEVER FAIL to do this, with a load either a/c's or electric heat depending on the season. It currently has 385 hours on it and has never failed to provide power anytime I need it.
A few times I have not been able to get non-ethanol fuel and had to put ethanol fuel in it. When I was back in an area where I could get non-ethanol, I ran the tank dry and refilled with my normal fuel/stabil and ran it for my normal 1 hour.
Works for me.