I was just reviewing this issue. After buying a Becker saddle (which I haven't tried yet) it's getting harder to find obvious places to reduce mass from my bike. But the Thomson Masterpiece is just so solid, with such a secure clamp, it's really hard to justify compromising that for 50 grams, especially when you look at carbon-railed saddles which are simply going to be a lot happier with a distributed clamping force than with one of these minimalist things which clamp the rails in two discrete locations.
In the Thomson post tuning
thread, WHO designs reported on a very trick Thomson seat post clamp which saves 30 grams off that already competitive post (180 grams for 31.6mm x long):
150 grams it right down into the New Ultimate range. I look forward to reliability reports on that clamp, however.