Starting to get the itch for a new tandem. (Our Co-Motion Robusta is going into it's 6th season and has around 25,000 miles). I like the idea of getting a bike 3-4lbs lighter, but admittedly most of the reason to buy a new tandem is just to have a new toy.
The bike will be used mostly for training and fast group rides, and we'll race it a few times a year. (State time trial championship, Masters Nationals).
My concern with the Paketa, and to a lessor degree the Calfee is frame stiffness. We got the Robusta, instead of a Macciato specifically because we wanted a stiffer frame. (Team weight 340lbs).
The Robusta is acceptably stiff. However people riding behind us say they see noticeable flex in the rear end when they're following us at speed, and a couple of times there's been enough frame flex to bother me to the point of slowing down. (However, those were both extreme circumstance, standing sprinting in the high 30's, attacking downhill, pedaling a high rpm in the 50's).
So we need to new bike to be at least as lateraly rigid as the Robusta, preferably moreso. The open frame design of both the Calfee and the Paketa concern me in that regard. My thought is the Calfee can be built, perhaps with some modification to address the issue. I'm concerned that we'd find the Paketa too whippy.