Did a 200Km or so highway drive today, well, it was 90% highway and a bit of running around in between.
Currently on 62% E85 (as reported on the scantool) the fuel consumption increased to 8.4L/100 (28MPG), on regular unleaded the same trip would have got around 6.0L/100 (39MPG). So is it worthwhile to run E85?

E85 @ 99cents per litre, costs me $8.30 to travel 100 KM's (at 8.4L/100)
Premium 98 @ $1.47 per litre would cost approx $8.82 to travel 100KM's (at 6.0L/100).

So it's not money savings in question here, it's the fact the engine seems so much happier with a decent amount of E85 in the tank.
I think the ideal mix might be around 35% - 40% ethanol.