If you're looking for something more portable, the New XPS 13 is in development and is supposed to launch soon. I follow the project lead's blog here: http://bartongeorge.net/
My hats off to the Dell team; they're very open about what they're doing, making better drivers etc. before launching the product.
For now I'm trying out a 2015 Chromebook Pixel with Debian GNU/Linux install..ing. Still working on it. It has a lot of the same problems mentioned here: - Suuuper glossy screen (basically a mirror with a dark background) - Limited keyboard: no pageup/pagedown.. even more limited than the Dell, it doesn't have a DEL key, just Power in its place... much key remapping will be required to make this usable. - No physical trackpad buttons, and that's a huuuge problem, because even Google's touchpad driver fails some basic tests of operation as compared to a Mac (e.g. cursor stutters its motion if you click while moving the cursor). The lack of touchpad buttons across most laptops now is shocking. - Keys are a bit shallow