" on probe stiffness under lateral and longitudinal swiping,  in simulation and experiment. With the exception of Fig 00, we see very little dependence on probe  stiffness. Even with Fig 00, it would appear to suffice to pick a good stiffness (lower values appear  better) and to fix it. The added value of varying the stiffness is by no means apparent.  The authors thank the reviewer for this comment. T