From what I hear you get better ramp scores, but they can also unload at funny (scary) times. I have never used them and do not intend to so this is just my biased hearsay.
They are not worth the money. Like said above, they are for ramp scores. On the trail they and unload at odd time, making your truck unpredictable at best. They seem to work okay on lighter rigs, like a samurai, but for a Scout, stay away!