ORIGINAL: MinnFlyer
Something that a lot of people don't take into consideration is that gasoline is MUCH more volatile that methanol, so in equally sized engines, the gas engine will produce much more power.
Personally, 120 is the cutoff size for me. At that size and above, I go gas.
Gasoline has a much different air:fuel ratio than glow fuel. Gas engines have about a 17:1 ratio, while glow is closer to 4:1. Therefore in equally sized engines you burn roughly 4 times more glow fuel than gasoline. OS rates their 1.60 (26cc) engine at 3.7bhp, while Fuji rates their 1.40 (24cc) at 2.2bhp.
Glow engines have a much better power to weigh ratio which is why you don't see gas engines on small planes.