We had DP with propane powered Onan, on a summer trip in 2012, using the roof top A/C, we had to refill the built in lp tank every 3 days, that meant moving the MH to the lp seller every 3 days,
Currently with this gasser, im using a champion portable dual Fuel generator, i have not used the propane option, propane is $3 gallon, Reg 87 octane is over $5.29 gal and E85 Flex Fuel "Ethanol" is $3.39 gal, im burning E85 in the Champion,
Ethanol 88kbtu gal , gas 116kbtu gal, 25% less energy, but cost 40% less $$, the engine runs cleaner,
But too keep it from being lean and running rough, i adjust the choke for smooth running , varnish has not been an issue , I'm full time , so No long term storage for the generator or fuel, does not have the chance to absorb moisture or dry up, gasoline or Ethanol,
For me gas has always been a better option than LP, and with current fuel prices, Ethanol is my best option, Gasoline is putting me in the poor house, its been busting my bank for months
Your experience might be different, its the fuel pricing and amount you will use versus availability and convenience, fixed location with natural gas or 500gal lp tank, against portable use locations storage transport etc.