One more question, guys.

Let's suppose I start the unit with a different microSD, not containing the ext3 partition (mmcblk1p2) referred to in the boot script.
This is the case when I have to plug the microSD in containing just the firmware upgrade. In fact that's just how the unit works: start the system upgrade process and it will look for the firmware img files in that microSD slot.

Now, what happens? The boot script is run and... ? Mount will fail and I am back to the original /data? Or, will the system hang?