I replied on a private message, but I'll also paste the reply (a bit extended) here for reference.
I removed Chromeos, and now I have only Arch in my Chromebook (installed in the internal eMMC). It works pretty well. Boots to desktop en 10 seconds, Chromium runs pretty fast, Libreoffice and Codeblocks run nice, etc. Unfortunately, forget about watching HD videos in Arch. We still don't have a working driver that allows doing it.
HD videos play nice in Chromeos. If you don't get rid of it (either by running Arch in a chroot, or by dual-booting), you'll still be able to watch HD stuff, but forget it otherwise. Outside of Chromeos, Youtube SD videos available in HTML5 also run nice in Chromium, but I could not run Flash based ones. I have not tested Firefox. Also it looks like
some Ubuntu people got Flash semi working, but information is not clear, and I had not the time to investigate it thoroughly.
I also managed to get the webcam working without a problem using xawtv. It works smooth at low resolutions (e.g. 320x240), but making it fullscreen causes a very low framerate. Also I have not tested any video-conference programs, and I think there is no way for example to run Skype (as it is closed source). Please someone correct me if I'm wrong.
I have also a very annoying problem (I don't know if it happens only in my computer, but I think I read other user having also this problem). Since I removed Chromeos, sometimes the Chromebook randomly powers itself on. When this happens, sometimes it runs until battery is depleted. Other times I open it, and find it powered (the white LED is ON and the netbook is warm), but it doesn't respond. Screen keeps black and doesn't respond to the power button. You have to keep the power button pressed until it powers off and then it works again. This never happened to me until I flashed nv-U-boot and removed chromeos...