The nice thing about AVS is that it isn't meant to just make things stiff. With S+ mode, when cornering it increases the damping force on the loaded side to reduce body roll. In any mode AVS will constantly adjust to improve the ride and handling depending on the road surface and how it is being driven.
The sport modes will increase the throttle sensitivity, hybrid battery assistance, and the weight of the steering. However it is only the 450h, with the variable gear ratio steering, where you get sharper steering as well.