I think this question has come up before at RCU and the answer given was that methanol supports the catalytic action, but other alcohols not as well / not at all.

In high performance motor sports, it's always been methanol, methanol, methanol.
Last time I checked it sold for $3.00 / gallon.

With .049s the prop governs the rpm and the fuel economy. It makes no difference whether it's a TD, Medallion, or Babybee....if the same size engine is held to the same load and RPM the mileage will be pretty much identical. This assumes the engine isn't throwing a bunch of fuel out the front bearing.