I have one on my new 29er Fuel 9 (comes with the bike). At first I didn't think I would like the extra weight. I think it's only about 275 grams more than the Thompson seat post I had on my Rumblefish. As everyone says, it's great to have the ability to lower it on the downhill. You won't regret getting it. I recently looked at the Thompson dropper post and like that it's not hydraulic (no messing with oil) but it does weigh more than the Reverb. Go for it.
Have one on my Remedy (stealth). Love it when it works...it's been a pain in the ass. Rockshox has rebuilt it, dealer fixed it, then I'm told it's warranty is up, then LBS rebuilt it. Just got back from 4 days enjoying the best of Oregon, seat post acting up again. I road a KS for two years with no issues.
Just my experience.
2012 Trek Remedy 9.8...Yep, the one with the little wheels.