In terms of ride quality, even in comfort, the mag ride is pretty crashy, there is a noticeable difference between settings however.
Compared to the EDC on my old e90 M3, or the PASM on the Boxster, it is really quite poor to be brutally honest, simply not in the same league from a damping perspective.
Interesting -EDC on my e90 M3 I found too stiff even on its softest setting when at speed (on a long drive to the country or something). It was OK in town, the RS3 settings all seem to be more isolating (comfortable) than the M3 and much better at speed but less controlled at slower speeds with secondary rebound not being well controlled - I actually think the springs could be to blame partially as many who have gone to MSS kits reckon it improves that secondary ride.