Well, whaddya know... I tried booting Chrome OS Flex from the USB port on the other side of the MacBook Air (the right side) and it's booted up fine; I started drafting this post using it.
My wife loves her (proper) Chromebook for online work and the ability to run Android apps. Flex doesn't support installing from the Play Store so Android apps are out; I wonder what benefit I could get from a Chromebook-esque device.
I need to find a decent editor and FTP client and then I'll be happy, do such things exist for Chrome OS? I've found some poor, basic ones in the Chrome Web Store but they're not ideal.