Getting KDE and Ubuntu onto this cheap Chromebook turned out to be surprisingly trivial: Google semi-officially provides a script called "crouton" (https://github.com/dnschneid/crouton) which installs a chrooted Ubuntu of your choice which runs side by side with Chrome OS, so you can flip between your Chrome UI and KDE with a single keypress. KDE, despite running off a SD card and having software-only OpenGL (a fault of the ARM xorg video driver, it can't currently cope with nested GL screens), is snappy enough, though it definitely lags whenever you open or close an application or do anything disc bound. In the end, those 0.5Mb/sec random 4k writes can't be escaped from.
I have to admit I am ending this weekend with a far more positive impression of Chrome OS than before. I had until now assumed it Google's feeble attempt to pretend to be an OS platform vendor in order to keep its engineers happy. Having actually used it, the lightbulb has turned on: Chromebooks are "good enough for most common uses" iMacs for an eighth of the price. The Chrome UI is unmistakably a clone of the Mac OS X UI, right down to single button trackpads. And while the hardware has pathetically miserable storage, Google encourage you to play around with the hardware through semi-official support for "real work" solutions such as a full blown KDE desktop. In short, Google now sell their own clone hardware in every major category that Apple does, all inferior but much, much cheaper. Apple are in deep, deep strategic doo-doo. If they continue to do nothing, I am confident in predicting another collapse within five years.
Speaking of storage, late last night a lightbulb switched on during my search for suitable SD cards: I was going about this all wrong. The ARM Chromebook has a USB 3.0 port which granted ain't great, but it's good enough to hook up a tiny mSATA SSD in an enclosure. So I picked up a 64Gb Crucial M4 mSATA SSD plus mSATA to USB 3.0 enclosure last night - luckily Amazon had the M4 on special offer - and I'll have spent only $30 more than I would for a top end 64Gb SD card solution, but the M4 is like quite literally 100x faster at random access. Running a compiler and IDE and debugger should fly on this, and weirdly in 2013 I'll be back to developing primarily for ARM again, just like I was twenty years ago :)
So Chromebook storage solved. This thing is my new portable code development solution. I only wish now that the trackpad didn't click itself every time I pick up the laptop by its front - such is the thin cheapness of the plastic that it flexes enough to click :(. In the end, I did spend only $250 ...