The only weakness is 13+ mph while going offroad where KDSS is in on-road mode, and washboards can make the ride harsher. But I think the theory there is you should be aired down enough offroad to make that prob go away.
Can someone confirm this bit is true - I haven't read anywhere else that speed causes the system to remain stiff regardless of the terrain. Presumably this would be why some are commenting that KDSS causes a rougher ride on washboard?
This video, although it's a LC, is still applicable to the 4Runner, as the system works the same. As you can see during the slalom part, the KDSS mitigates body roll much better than a standard sway bar. Therefor it's not working like a 'standard sway bar'.
YouTube
The video Hydguy posted seems to suggest that it will also work to smooth things out in a high speed uneven scenario.
I didn't have the option of KDSS in the TRD Off Road I am getting later this month (they all come with it in Canada) but I probably would have went with it anyways. Just curious.
Thanks in advance.