I ordered the long travel for the Sondors Thin (27.2mm seat post). I was happy with the included shim for the Fat bike, because I do have both models. I can use the one Thudbuster for both bikes. I have a 29 inch inseam, and set the seat for a full leg extension. With the higher standover of the Thin I was concerned with the seat being too high, but the fit is fine, with a little adjustment downward remaining.
The Thudbuster provides a supple ride to what is quit a spine rattling experience on that Thin bike. The long travel does suck up those big bumps, without any noticeable change with leg travel, and the sensation is of a rear wheel suspension. However; cold weather does stiffen the elastomers, and lessens suppleness, but there is still adequate comfort.