It's been said many times - the engine takes a almost 2 times less fuel running on gas/glow than on methanol. This is the saving. The power is lower just a bit on gas tho. In my case I just mix 5 volumes of gasoline (3.4 dollars a gallon) with one volume of 15% glow fuel (15 dollars a gallon) - so I pay about $5.40 for gallon of gas/glow fuel (with nitro and oil), but from 8 oz fuel tank I have over 15 minutes of WOT on Poulan 25cc.

About Perry carb it is lighter, but I believe you still need to provide some kind of pump for fuel or preasure the tank. By accident I found that Walbro pump is very effective. I forgot to unplug the vent and after the flight my fuel tank wass ssucked in - never returned to the original shape.