Nah Adam, ethanol does burn slower than petrol. It also burns cooler due to the hydrogen bonds in etOH, which requires a lot more energy to vapourise than petrol. Explains the lower EGTs when running etOH huh? Fact in point is bubble point of etOH which is only C2 is 70degrees, it is a trend that the more the carbons, the higher the bubble pt (high school chem i assume).
Petrol is basically C8, with various isomers and aromatics added in to increase octane rating, but they all have roundabout 6 to 8 carbons, and no oxygen in the molecule itself. Petrol itself boils at 90degrees, but the components are largely C8.
We can look at vapour pressure and heat of vapourisation to understand volatility. 896kJ of energy is required to vapourise 1kg of EtOH vs 298 for octane, which is the closes to petrol. This, is why it burns cooler and slower. Or at least why i understand it burns cooler and slower. I'll have to look up activation energies to further explain why etOH burns slower but i cbf now.
And that is why, it is probably better to go a hotter plug when you're using etOH as a fuel.