What I meant was that over time the springs from any suspension will settle (FYI: my S4 Suspension is fully settled). Therefore, if your suspension hasn't settled, then the resultant drop, when switched to the S4 suspension, will be more (it will be a "noticeable" drop). If your suspension has settled, then the difference will be less - there will be a drop, just not as much.
Furthermore, if an A4 has been fitted with a Sport suspension, then the resultant drop with the install of an S4 suspension will be minimal; both the A4 Sport and S4 suspensions are close in height.
Does this make sense now?