I see propane down ratings from 6% to 8.2% from gas performance. The bigger unit had the larger loss. I looked at tri fuel generators and compared the rated watts on each fuel. I could also go gas and just haul the fuel daily or get a bulk tank for that too for fuel truck deliveries. If I went with a tank I'd need at least 150 gal because my supplier will not deliver less than 100 gal and I would not want to run out before ordering. The propane thought was because they deliver lesser amounts and it never goes stale like gasoline.