Wait for the new version of the xtherm supposedly coming out this year. Was at the last backpacking expo. Lighter than the current version, warmer, and QUIETER (the most important thing). I'll probably have to upgrade my current xtherm when it comes out.
Gotta correct this. Turns out I was confusing the Xtherm for the new Xped. The Xtherm is getting a better covering to make it more quiet. But the Xped winterlite down is the lighter/warmer pad that I was thinking of. It's a bit heavier than the Xtherm, but the R value is a substantial bump.
Sorry for the confusion.