I have no experience with ethanol in race engines but I do have with its cousin methanol.
Running methanol on Weber carbs we increased the fuel jets by close to 50% and used 50% more fuel. I cannot remember the change to the air correction jets. Running lean would detonate a piston very quickly. You also had to add a synthetic oil (or Castrol R, loved the smell) to the fuel to avoid complete wash down of the cylinders. Regular oil would not work as it would not mix with methanol and it would be the same with ethanol, regular oil being mineral and the other vegetable based or synthetic. The use of a percentage of gasoline probably eliminates this problem. Methanol attacks rubber so all fuel lines etc. had to be neoprene based. I expect ethanol is the same. Fuel bladders may have to be a different composition than normal. Methanol and I expect ethanol also attacks aluminum. When we ran Webers, before we switched to injection I drilled the bottom of the carbs and installed radiator drain petcocks so we could dump the methanol from the carbs after running. Race check list included making sure they had been closed again!
We also ran some Acetone in the mix especially in cold weather to make starting easier. That we kept that secret from the others! We often, in cold weather, had to spray gas into the injectors to get the engine to fire.
The addition of a percentage of gas would ease this starting problem and ignition systems have improved over the last few years.
As an aside two stroke engines DO NOT like ethanol. We used to be in the tree stump removal business and knew all the tree companies. When using gas with 10% ethanol they started blowing up their chain saws.
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