The harshest ride on any tandem is for the stoker.
Pilot sits in middle of the frame and whether steel, alu, ti or c/f, he gets the 'softer' ride. Stoker takes all the road shock/bumps from rear wheel.
That's why many stokers need/demand a suspension seatpost on most tandems.
Fortunately we've been riding tandems since way before suspension seatposts re-appeared (it is not a 'new' idea/invention). We have never owned a personal tandem with suspension (Kay must have a tough little butt!?) but have ridden test tandems with several kinds of suspension posts. Will not argue with stoker Kay when she considers the c/f twicer a 'most impressive and comfortable ride.'
Yes, Co-Motion builds a great tandem; we've owned a custom Co-Mo (built in '93) and put 57,000+ miles on it. A fine machine!
Frame materials have greatly improved since the steel 1975 Follis tandem we started with!
Pedal on TWOgether!
Rudy and Kay/zonatandem