E-85 is a PIA IMO, if you have ever run it in a vehicle you don't use "often" unlike a FlexFuel daily driver where its mostly OK.
I have run it in my race car, my hot rod, my sand car, and set up a few LS sand cars for it including FlexFuel sensor on the ECM... If you really want the HP and are willing to deal with all the extra work that comes along with it, its an affordable alternative to race gas (and 02 sensor friendly - kinda) especially for anything boosted - its amazing and 40% more fuel consumption is worth it.
I agree most people that are not trying to toast their buddy with a Canned Ham Turbo on E85 won't need it or bother even if they have the SPPED key.
Where I disagree is that $1250 or even $2000 is a deterrent to anyone that wants more HP, especially if its financed ... Seeing some people signing paperwork for ~65K RZR's has convinced me. its like a "middle-aged guy" buying a Red Corvette.
I still believe the SPEED if it makes it to MASS production is the best value in the SxS market for the high end, if not the best overall design