You might check on the W220 forum, '99 - '06 S class. Many of those cars are having failed airmatic systems now that they are 10+ years old. Some owners might be making that switch.
I believe you will get much more body roll with 4 "independently" sprung corners. Vibe isolation will be less effective also, especially with those 20" wheels. Weight transfer, during acceleration and braking, will also be affected but maybe only noticeable if you are a "spirited" driver. Does your '06 have 3 suspension settings?
I bought my car last year on Sunday, Monday it was dropped off to my buddy's shop for a coilover swap (nothing was wrong with my Air) I just wanted to get rid of the garbage Airmatic, best mod I have done on my CLS so far
Air suspension is the only reason why I opt to buy a Mercedes vs. other comparable cars lacking it. The ride is smoother and you don't feel the road vibrations...
My dash cam with vibration sensor never registers false accident-recording when using it in my airmatic ride, but it captures many false ones when used in other coil equipped cars. I have to decrease the sensitivity of the dash cam sensor at that point.