Biggest problem with E85 if I understand it correctly is the fuel line compatibility to the corrosion of E85 vs E15 or lower.
If there is no deposit in the valve, manifold, etc the engine will handle it right. Most problems I heard about E85 is 1) it has less energy content than regular gas so it has to be cheap enough to justify, and 2) it causes extra intake valves deposits in some engine with direct injection and need expensive cleaning, 3) it corrode the fuel lines more than regular gas, 4) you can't find it easily outside of corn farming area, 5) it is about politics and people don't like corn, thinking that it is bad for the environment or it is a government subsidies, etc.
Most fuel lines after ~2005 should handle E85.
Harder on fuel pumps if they aren't compatible same with valve-seats and valves, increased wear.
Have not heard/read anything about IVD. Hard to believe.