Ah, you had turned it on :-) And actually the only thing that will get really compressed is the empty space in all partitions. /system itself has maybe 150 MB of data and the other images are peanuts, basically.
An empty 8Gb usually becomes < 200kb.
And if you have the screen off while plugged basically anything will charge the tablet. When you turn the screen off, also the processor scales down and with it everything on the board. I'm quite curious to see battery life when scaling is implemented while awake (when the GPU works).
Add: Well, at least I now know where the repos for the recovery are.
http://forum.cyanogenmod.com/topic/3...y-on-kobo-vox/
Will have a look at it when I receive the SD and can dissect the system image properly.