Thanks, that's very helpful. That would explain why the firmware version now seems to be out-of-step with the logic board.
Is it important for the ipod firmware to be consistent with the particular logic board, do you (or anyone) know? i.e. would I be best advised to go ahead and restore this ipod with iTunes, in order to get it back to 2.0.5, which I _think_ is what the ipod the board was from was using. As I understand it late iPod Classics with 2.0.5 firmware have slightly different hardware to those with 2.0.4, but the difference in the two isn't major, and I only use Rockbox anyway.
Just reluctant to go through all that if it's not important, as it takes such a long time.
Alternatively, does anyone know if there any way to restore the correct firmware version without completely wiping the ipod and starting again?