I've hardly touched my MB Air (2012 refurb) since I got the Chromebook. Small and light enough to throw in any bag/backpack without care, cheap enough to not worry about theft.
I don't mind it being the same CPU and RAM specs as the original; I don't need much for the Chrome browser and a SSH session to the beefy server where I do most of my work.
Also owned the C7 Chromebook for a while; upgraded it to SSD and 8G of RAM, but it felt like an abomination with the fans, heat it put out, etc. Sold it to a friend, who absolutely loves it.