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