Very interested in the pro's and con's. Our old tandem did not have sufficient room to use a shock absorbing seatpost. I was thrilled when we bought our current bike which came equipped with a Thudbuster SL. The ride seems a lot easier on my rear but I wasn't sure if it was the shock absorbing seatpost, steel instead of aluminum, the longer (and better fitting cockpit), or other factors. We do long rides (completed a 400K brevet on Saturday). This thread has me willing to experiment replacing the Thudbuster with an Ericksen SweetPost ti seatpost off one of my single bikes for a couple of rides. If I don't need the Thudbuster, I'd rather lighten the bike. Plus as someone mentioned, the movement of the seat effects the rack or bags. We used a small seatpost bag this weekend and although it looked fine without us on the bike, once I mounted the bag rubbed the tire (and the tire just about rubbed thru a section of the bag's strap).
For the riders who are bouncing, I wonder if they are using the right elastomer. As I recall, the bike came with several for stokers of different weights. I definitely do not "bounce" in the air when we hit bumps.
As an aside, I find a huge difference in comfort using the same saddle on a single bike and the tandem. I haven't figured out why, but a saddle that I find comfortable on one of my road or time trial bikes can be misery on the tandem. I keep experimenting with different saddles to find one that is comfortable for the 12 and 24 hour rides we do.
GLA, please send some detailed posts about your ride in Switzerland. We are hoping to ride there this summer or next.