My opinion it will not help you any to run the higher octane unless you are pinging (which you may not even be able to tell) Higher octane fuel does not make better horsepower or mileage but it allows you to use higher compression or boost.
Now if your computer is retarding the timing for bad fuel and you put higher octane gas in there it will help both performance and mileage. I will not hurt anything except your wallet to run the high octane fuel unless it has lead in it. I do not see how 100 octane could hurt any motor but if you have a motor built for 100 and you run it with 87 it will definalty hurt performance, mileage and even the motor. Clear as Mud?
If you can get Jet-A cheap, you can try mixing 20-33% with E85
It's "easy" to run on kerosene btw, all you need is about 5 headgaskets, or to slip your timing belt by a tooth so you've only got about 6:1 dynamic compression ratio... hmmm wonder if you could stack A LOT of sparkplug spacers ....... just kidding really, you'd need to find about another 40-50cc with them... though if you had a 8:1 motor, it might be plausible to find another 10cc like that... and it might run eventually, if you wrapped the fuel line round the manifold, and did the flaming rag in the intake trick to start it....
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice