I run both e85 and 93 in my forester. I have deatchworks 305 fuel pump and 850cc injectors plus a tune. For the most part I run 93 because it is more efficient for day to day driving, but e85 is just cheap racegas and should be thought of as such. I make considerably more power on my e85 tune at 20psi than I do on 93....much more. In fact we had to dial things back to 16psi because the clutch was slipping at 20...16psi still makes more than my 93oct tune. So for the money - hell yes, get the addl tune for e85 but dont rely on it day to day.
As for the argument that wmi and pump gas is better than e85 , I will say this: I dont have to worry about running a wmi tank dry when my foot is in it. And if you arent tuning for the wmi and using it as a safety, you arent going to even come close to e85.
The different classes of e85 are there for temperatures and startup. More fuel for winter, hence the e70. This is on caveat of having an e85 tune. Your tuner has to leave you that margin and cant go tuning you on the ragged edge using class1. You should never use a pump that says "Minimum 55% ethanol" unless you test it and know what you are getting, plain and simple. So there are reasons its just not practical day to day but no reason not to pay the extra $100 for the addl tune while you are on the rollers.
..:: sleestak ::..
"Our mother of blessed accelleration, dont fail us now!" -- Elwood Blues