Ethanol burns way cleaner than gasoline. I wonder if the reduced soot from running E85 equates to less carbon build up on the valves, less "coking." An issue inherent with the DI engine design.
Id like to see spent oil and vapor from an engine running E85. You have a catch can OP?
Thanks for the insight OP, E85 might be something I do in the future. Being in SD there are a few stations which sell it.