Well 360 Premium = Hard Drive, No EEPROM
360 Core = No Hard Drive, EEPROM
Someone should pull a little switch, de-solder the EEPROM from the Core, and put on the Premium Hard Drive. Then solder on the EEPROM for the Premium (guessing that there still is a spot for it). If it works, it shows that they both act as the holder if information, even tho the Core was proven to work without the EEPROM. If it doesn't, it means that one of them would cause a crossing of inconsistent data, meaning that they have to match or change for it to work.