One thing great about booting from MMC, is you can easily backup and restore your entire operating system. I just use cifs to RW mount a remote share. Once mounted run dd if=/dev/mmcblk0p2 of=/mnt/remote-dir/mmpblk0p2.img

Note you can also mount this image on a linux system mount -o loop /mnt/remote-dir/mmpblk0p2.img /mnt/image

This will backup the entire mmcblkp2, which in my case is an ext2 partition. To restore just do the reverse, I make a backup before I do anything risky.

That flash partition is like having a rescue disk. You can also mount the ext2 partition from flash boot and install packages on mmc partition you could normally not update because they were running.

Anyway, my 770 is still out for repair, I will play when it returns.