"Bless her little ol' heart...but she was just such an idiot." Yeah, I know how that line goes.
I have to say that during my hike down through the Shenendoah last October, when the temps were still rather warm, it was nice to save that 10 ounces from my pack. Well, that and a few other small improvements made a noticeable difference.
So now I guess I'll be experimenting with how low I can comfortably go with the Trekker, and when it's time for my Xtherm. I too have used silk weight Polartec under my woolies and I think that does help a little, and I also keep a couple of snacks tucked away -- or my entire food bag, more likely -- but I can't say that I've ever felt that help me warm up. Rev is right: once you're cold it is really, really hard to warm up again.