Bacciagalupe

I've been riding a Dahon Mariner (basically a Boardwalk) for a few months now, including on some longer rides -- I may even start doing centuries on this thing. The position is generally pretty comfortable, but I'm feeling the bumps a lot more on this bike than on my hybrid, which has 700c's, front suspension and a seatpost suspension.

I've noticed the higher-end Dahons have suspension seatposts and/or front hubs. Is there any point in putting a suspension seatpost on this bike, and/or any tradeoffs in terms of riding efficiency and power?

Thanks!
- B