I tried it a month or so ago at about E25 and didn't have an issue other than fuel disappearing faster
I only have one station I know of with it so I don't run it a lot since I can't get it when I am hammering the mountains.
I just filled up with E30 by the calculator. I left the "at least 10% eth" set at 10 so then to be at E30 the m2 would be 10 gal 93 & 3.7 gal E85. So thats what i did
Reflashed the car to stg 2 E30 and will see what happens