Excellent news! I've proved to myself that it's mostly down to how you drive.
I picked up my new (to me) Mito 155hp today, I've managed to get 42mpg so far but the Dynamic setting won't see that last for long!
Yes you are right, the obvious things are that it makes the accelerator far more responsive and the engine appears freer revving, it weights up the steering and does something to the traction control as well. On cars with active damping it stiffens the suspension as well.
I'll get kicked out of here for talking about MiTos in the 156/147 lounge!