Even for cassettes? My understanding is, the weight savings on DA cassettes are primarily from using lighter Ti for the larger sprockets where Ultegra uses harder wearing but heavier nickel-plated steel ones, the rest of the cassette being mostly identical (except for the lock rings). Am I wrong on this one?
Dura Ace 9000 has a nylon carrier for the middle cluster of 3, which saves weight. This cracked in early versions, including mine. That kind of proves you right in a round about way, had they kept that design. Haha.
Lots of new 10 speed 12-27 Shimano cassettes at Wiggle, including 105, Ultegra, Dura-Ace, most for pretty good prices--they have facilities here and in the UK, shipping is fast (often less than a week even from UK) and sometimes even free depending on their specials. Of course here in the land of Shim, lower prices might be had (Rakuten JP sometimes), but Wig's prices are surprisingly competitive, AND they stock a lot of 10 spd stuff.