I must say, that I was a bit leary about ordering the optional KDSS upgrade, especially considering that I had to get rear seat DVD and third row seats as well (two options I did not want).

In any case, it was worth it. It severly decreases body roll and even with the reasonably high profile Michelin Cross Terrains it handles drastically better. Now I mention this with 2 caveats; You cannot get the Towing package (why, I don't know but I'd love to hear an answer) and, I cannot confirm that in single wheel articulation moments, it achieves better travel.

The second, can certainly be tested, and I intend to do so, however I just don't have the guts to go and beat on my GX just yet.

All the best,

Andrew

I also was concerned about getting on option which had unverifiable feedback. I drive almost everyday, over mountain/canyon roads, and the only word to describe the control is AWESOME!!! When I first discovered that the body has almost NO perceptible tilt at speeds to ridiculous to state here, I could not help but smile. The handling is better than any Range Rover or X5 that I ever drove. The limitation on the towing, must be due to the active control of the suspension (shifting weights and stresses) that would probably break if exposed to that situation.
Anyway, this control system is more than I expected it to be. You almost forget your in an SUV and not an M5. I hear that the new LR Discovery now has this same option. I am curious that they think of it on that side...

still learning more about this beast ...

I love it also. Very smooth. A/B'd it with a friends GX470, and I do like the ride better with the KDSS.

Haven't had the desire to take it off road yet (?ever)

Overall, worth it, but still hard to find.