Ok guys, so my question is, is it worth it for a stock R56 to get a tune for E85 and run it or should I just stick to using 93?
I don't think you can do it. The car and its computer /fuel supply will not support it without major $$$$.
From what I remember, E85 and the MINI engine doesn't play well together. Someone else may have a better idea and more info.
You'd need a new or flashed ECU, new injectors, new pretty much everything fuel system related.... I wouldn't. Now on the other hand, if I had a mid-90's Subaru that I didn't care much about and for which there are plenary of after market ECUs, injectors, and so on that are specifically made for that kind of thing, then.... I probably still wouldn't bother. I say this because when I had a mid-90's Subaru, I thought about doing this and then didn't bother.
I made the switch. For a track car, it's worth it. For anything else, probably not. As has been noted, you'll need a new fuel pump, rail, injectors, ECU, etc. It's not cheap.