Regarding the characteristics, you're right when discussing the stock torque and power curves, but as soon as the coding is cracked and somebody optimizes a tune for E85, look out! My dyno from earlier this year with a blend of E85 and 91 octane, netting an E60 blend, is shown below.
Note that this is with my daily driven fuel blend and tune as better numbers are achievable when cranking up the boost and more timing advance.
I hope the S55 torque curve is like the N54 but even better, as I love mine. It's a tire shredder, but man is it fun to drive.
Link to Video of Dyno Run shown above