I've been using Lenovo X1 Carbons for about 4 years (since they came out) and love them. Super light, enough RAM and CPU, great keyboard (after 3rd Gen...), has a TrackPoint (which I require). I'm been using Debian exclusively since 2008 and Gnome 3 since 3.4 or so. Highly recommended, though HiDPI support is not perfect...