I've been contemplating a damper too, though haven't decided one way or the other. I'll be interested to read the comments in this thread; I know the guys I ride with and firffighter swear by a damper for the terrain we ride.
One question that's come up recently in my pea brain; would it be better money spent on getting the CF bars from Twisted or Flexx bars rather than a damper? I know we're talking two different things, but the idea of getting some type of flex bars is appealing as I deal with arm pump and fatigue from the vibration and all the rocks/roots we have out here.