the xreas suspension is a hydraulic system which links together the diagonal pairs of shocks on the vehicle (front right to rear left, front left to rear right). it borrows fluid from one to give to the other when the latter is under more compression. it helps the tires remain in contact with the ground and prevents body roll in turns and pitch over bumps.
it was designed to help on-road handling. imo the difference is night and day and worth the money.