Just got it last night, and had a short time to work on adjusting the fit, and getting a ride in. So the conclusions are still very preliminary.
As for working with Co-Motion that all went well. The bike was delivered within the time range they estimated. (8-12 weeks.) The bike was as spec'd (except for the tires which were spec'd as 25c, and came as 28c's.) Co-Motion did ship the wrong seatpost, and left out a shim for the stoker's stem. This was discovered Monday afternoon, and replacements were Fed Ex'd and delivered Tuesday morning.
The Bike is going to fit correctly when its all dialed in, so the measuring/ordering process worked well. The only problem is the seatposts have too much setback for me (the captain), and I may have to swap out a post with less setback.
The Bike is beautiful. In my personal opinion the 2 tone fade worked out really nicely, and was worth the $100 upcharge. Unfortunately, there's a slight chip in the paint. I'm not too worked up about it. It was going to happen someday anyway. The LBS, however, is going to see if Co-Motion will do something by way of compensation.
Weight is just about what I expected at 29lbs 14oz. Co-Motion specs it at 27.7. I'm sure they measure off a 21/18, and ours is a 22/19. Considering the slight larger frame size, and adding 396 grams for two sets of speedplays (and the heavier 28c tires.) would indicate that Co-Motion's claimed weight would be in an acceptable tolerance range.
As for riding it, it is Night and Day between the Co-Motion and the Burley. 20lbs lighter and markedly stiffer, really shows up in accelerating the bike from stops and out of corners. The Burley is like a Dodge Durango, and the Co-Motion is like a Porsche.
Cornering, it definitely turns in much quicker. The combination of the Alpha Q tandem fork, and FSA bar and stem is way more stiff than the Burley's setup. The Rolf wheels also feel plenty stiff even with the low spoke count.
The Dura Ace brakes stop the bike extremely well, and I'm doubting the need for a disc now (but will reconsider that after some mountain rides.)
I tried to purposely induce "stoker wag" (jumping on the pedals, intentionally leaning out of synch) and I really couldn't get the frame to flex, at least to any degree comparable to the Burley.
So I guess this report tells you that a 2008 Co-Motion Robusta is light years ahead of a 1994 Burley Duet, which you probably could have guessed.
Perhaps after some more rides I can post something a little more insightful