Did you perform a comparison on a corner? i.e. Fwy entrance ramp.

I'd suspect that an 09 w/ AD will corner better than an 11 w/o AD. I'm assuming that slight adjustments were made to the suspension for the LCI but am not certain.

My 08 w/ AD corners very well, but I can't say that It feels "harsher" when in a corner due to AD being active. That may be in your head.

I'm coming from a fully modded (suspension-wise) Infiniti G37 with coilovers, camber kits, sways, and braces. The ride in the X5 Sport with AD is "cush" compared to that.