I have the Lithia. I could do with a little less padding up front, but I don't feel it has too much padding under the sit bones. The longest ride I've done on it is 105 (each day, two days back to back) - no sitbone trouble, a little minimal soft tissue pressure/rubbing. It was beautiful for my 64 today. I'm sticking with this saddle for now, but when it's due for replacement I'll probably get a Jett.
Flur, how soon do you plan to do your first century? Might it be possible for you to start with a Lithia and then "graduate" to a Jett as you get more miles and your butt gets tougher?
Speed comes from what you put behind you. - Judi Ketteler