I am using the ST with the Swift, with the extra-extra-long seatpost (507mm compared to the XL's 403mm):
http://www.bikeforums.net/showthread...ght=thudbuster
There are three elastomers to choose from. At 195lbs, I use the black one. You'd probably want to use the white one, at < 100 lbs. I'll trade you a white one for a black one if you decide to go for the ST
The ST smooths out the road bumps quite well.
The ST weighs less than the LT.
The ST is simpler to configure/tune than the LT.
Regards
T