I have not ridden the Thudbuster but the guy that showed me this seatpost has used both and is very experienced in terms of equipment and physical issues. His opinion was that while the Thudbuster was a good option, the Cirrus Post was far superior. His reasoning was that the saddle was mechanically isolated from the bumps by the float mechanism.
Living life like there's no tomorrow.
http://gorgebikefitter.com/
2007 Look Dura Ace
2010 Custom Tonic cross with discs, SRAM
2012 Moots YBB 2 x 10 Shimano XTR
2014 Soma B-Side SS