Cannondales are nice tandems but not known for smooth ride on the rear.
I would ride it for a while and get the Thudbuster if needed. We had one our Santana which was an aluminum frame.
A saddle with more padding might also help, my wife uses a Terry butterfly gel.
Storage is nice to have on a tandem for tools, food, clothes. We have a large JAAND bag on the rear and a bag on the stokers stem.
The JAAND bags are really nice.
We use and like Conti GP4000 tires, not sure what come stock on a Cannondale.