Saw an ad for a buffalo mountain shirt on the F/S forum and it reminded me how toasty these seemed when i saw one a couple of years ago. Being a skinny git i suffer with the cold and struggle to retain heat, and these sound ideal for a number of purposes. Unfortunately no one stocks them anywhere near me and mail order is the only option, does anyone know if they will fit under a Savanna 2? The savanna isn't particulary tight as i tend to layer up well in the winter anyway but i don't want it to make me feel like the michelin man and hamper movement. Anyone wear one for riding?