I know you're asking about it on the JK, but the previous owner installed it on my 05 TJ Rubi and I love it. It's nice to have a choice it terms of "on the fly" dampening. I won't lie, it's sutle in my mind, but definitely noticeable. The only settings that I have really used are the highway (usually what it's kept on), sport (used it on some curvy roads... don't expect racecar type handling haha, but it was stiffer and less sway), and off-road (only used it on a few dirt roads near my house... can report back when I actually get some time to four wheel with it). The other two settings I have yet to use. Because the previous owner did all the work, I'm actually going to stick with the Rancho's when I lift it just so I can continue to use the system. Now, would I install this system if it didn't have it to begin with? Um, maybe, but more than likely not, but then again... I really do like it and use it quite often, so I guess it would be a 50/50 chance.
A couple things to note:
-The previous owner bought it off quadratec when they were running a special on it (which is why I think he bought it)... they threw in the whole system or at least part of the system for free if you bought 4 shocks (I think that's what he said)
-The previous owner also put in a toggle switch to turn the pump on and off. Basically when I get in and start the Rubi, I flip the switch to turn the pump on (which puts the shocks at the last dampening setting you had it at) and when I turn the Jeep off, I flip the switch to turn the pump off.
Hope that helps even though the system is on my TJ. If you got any questions shoot and I'll try to answer them the best I can. Oh... lastly, when I was looking into exactly what the system does and what not I found a thread... or website that gave a review and/or detailed directions about it, but for the life of me I can't remember where I saw it. It's out there though.