vod_warranty: nice and detailed instructions, good work!
One comment though: my colleague (Linux sysadmin) tells me that it is not very reliable thing to copy a live system disk in Linux/Android: the disk is being used while you are copying, so the image will not be consistent. At the very least, he advised to run fsck command on the created image partitions. Better still if all the partitions can be remounted as read-only before running dd. It may generate some error messages, but it might work. Ultimately (and if you disassembled the unit anyway), the only robust way is to properly shut down Kobo (>10s Power button), disassemble it, take out the internal SD card, and make an image of it - first to the hard drive, and from the hard drive - to another SD card, where it can be re-partitioned using parted or graphical Gparted.