with Clonezilla
Interesting idea. I was thinking about trying CloneZilla or Macrium Reflect recently..
Macrium can expand a certain volume to any size based on available space on the destination drive/device, just before actually doing the restore.
It would also be good to use a serial console (if the mister has this? kind of like an enterprise network switch) to show where the boot process gets to, on cards which dont boot after running the migrate_sd.sh script through. Sometimes I can run the script a second time - and it works. This smells like a dying SD card.. The script is flawless it cant really mess up!