It's pretty risky to tune your ecu for 100++ ron gas unless you always use this type of gas (how much more does it cost?) and have a wideband mounted all the time for real time a/f ratio indications.
It would be great for drag races and rallys though
I've a wideband (offcourse!) and a tunerview with al the information I need. The plans are to make 2 fuel maps (one for normal euro98 and the other for E85). E85 has the same prize as normal here (and not everywhere is e85 but it's upcoming) euro95 but it won't be that economical.
But you can make more power with e85 than euro98 with a good tune
Still thinking of going E85 as well myself. Though there should be more powerfull mixtures with lower ethanol levels... or so I heard. More like a 30/70% mix or vice versa.