We bought a Thudbuster ST a couple weeks back and so far the stoker likes it but it has messed up her saddle height and fore-aft position because it naturally sags a bit back and down when you sit on it. We feel like we have to re-fit her to the bike again.

That said, I was pleasantly surprised to find out how much it damps the rear wheel, which benefits both captain and stoker on our very stiff AL Cannondale.