firmware information is saved in the flash memory of the console, so regardless of the thoroughness of formatting the drive, changing the drives, etc, if you have 3.56/3.60, you wouldnt be able to restore with a lower firmware. the ps3 itself would say that you need to update with firmware 3.60 or higher.
even if you try to 'update' with a lower firmware, it just wouldn't work and will give you a corrupt error (cant remember exactly what the code was).
if you put a 3.55 formatted drive into a 3.60, it wouldnt be able to read it until you fix the file system through recovery mode and it'll be on 3.60 once it's done recombobulating the energymotron... or whatever.
found out through experience.