One option would be to check out the Kirk or Markins replacement baseplates that get rid of the center column. If you can live w/o the center column, you could get a roughly equivalent weight reduction to the 1257, plus the benefit of some added stability. The other option is to evaluate the ballhead you're using. The Acratech Ultimate and Markins appear to be the best lighter ballheads, with the Kirk BH-3 being a few ounces heavier.
The weight difference between the old Gitzo and the new Gitzo is only 0.3 lbs. That's roughly a cheeseburger for us Americans...
Interesting hints and reference point.
I do have an Acratech ballhead, now used with my Gitzo 1028, but find it to be a bit too much of a compromise as a serious set-up. Besides, I use a lot the panoramic head of the BH55-PCL.
My best guess for a lighter high end tripod combo would now be the Gitzo 1257 with a Markin replacement base place and a RRS BH40 with PCL... I don't think that I can afford to spend again this kind of money though.