I just had those exact wheels built and mounted on my bike. I had mine built at Universal Cycles, Portland, OR. They are a great bunch of folks to work with. They also had a good deal on the older Ultegra hubs. I just checked and they are also out of the Dyad, 36 hole, silver, but still have the hubs. Check out their interactive custom wheel builder feature. I have only ridden them two times. but they seem like a nice setup. I'm running them with 32mm Schwalbe Marathons, which are quite a bit heavier then the 28mm Ultra Gatorskins on my other wheels. It was hard to give then a real fair evaluation, but I did notice the extra weight. I also put the Marathons on my wife's touring bike, and she could also feel the difference. After a lot of research and comparisons, I chose the Dyads for all the reasons you mentioned, and I don't think that I'll regret it. The bike is a Bianchi Volpe set up for touring.

http://www.universalcycles.com/