RE: 31 CC Gas vs Glow
Dave,
With gas you have much less cleanup. You don't worry about hot fuel proofing. Gas is still cheaper. You can locate the tank on the CG. Fewer dead stick landings. Better fuel draw. You save on glow plugs. The prop hub is easy to get and cheaper. You don't have to add lead to the nose of many scale planes. You set the needles once a year rather then before each flight.
Dave