e85 provides 30% less energy than 10% ethanol,,not MORE.
Higher octane fuel provides benefit only untill the point that detonation stops,,no benefit past that.
I use a combination of timing adjustment and 115 octane and more so than higher octane I use meth injection in full race motors.
I use the least amount of octane possible to deliver max torque and hp,87 octane if and when possible and then adjust timing,with a knock sensor .
Ethanol is hygroscopic (water attractant) and if not stored properly will take on water and instead of running it through the fuel system will phase seperate in a fairly short period,which will then sit in fuel bowls and fuel tanks.
I prefer to not have this as an issue and use a controlled source( water/meth injection).
I personally see zero benefit to e85 and think its actually the reverse direction