I know everyone doesn't full time and can't do it, but I'm running my ONAN 5500 DVAP right now for it's every first day of the month one hour run under load. I use only non-ethanol fuel (and if I do have to use ethanol fuel I make absolutely sure I run the tank dry before I fill it back up with non-ethanol), add StaBil Marine formula with every drop of fuel that goes in the tank, but the main thing is the monthly run under load.
Right now I have 389 hours on my Onan using the above procedure and it has never ever failed to start easily and works just like new. 50 minutes more and I will be back on shore power.