For anyone still following, I am looking into this with some success. I have two different ML-1 systems that I have been able to obtain the bitlocker keys from. It appears that the keys are different on each drive. Cloning the drives do not work. Swapping the drives in either system sends me to a factory reset screen which then fails, but the drive works when placed back into the original system. So it appears there might be both a hardware and software component involved in generating these keys.
Using the obtained bitlocker keys, I was able to fully decrypt the drives. It appears there is a games partition, a recovery partition, and a logs partition. Nothing remarkable in the logs about encryption. The game boots into the menu and the games work fine. However, cloning a decrypted drive boots to the menu also.....but the games simply exit as soon as you try to start them. Looks like there might be something else going on besides the initial encryption.
I am interested in being able to make a backup of these drives which inevitably will fail. I would love to get this running on SSD but the only drives I see available online are the platter-based. Has anyone been able to get any closer than me?