Don't know about road, but I loved it on my mtb. My hardtail was fine in Boise, but when I moved to Phoenix I was riding REALLY rough trails on every single trip out and was being robbed of momentum trying to get over the rocks seated. The RockShox mountain post allowed me to remain seated in the rough stuff (everywhere in South Mountain) and really did make me faster and more comfortable. That thing really did it's job in Phoenix.

I have thought about it for my road bike but really can't see much need.