The HD recordings at the very least will be encrypted with the decryption key required to view the content which is unique to the box. The key based on what we know from the the earlier HDR-FOX-T2 is derived from the box unique MAC address and it’s serial number. If the box was a HDR-FOX-T2 (Freeview box) there are ways you can make all recordings usable on other kit. We can’t discuss this here, but it’s not going to help on the G2 Freesat boxes.
No idea if SD recordings are recorded without encryption, you would have to try this out. The File System is Linux EXT3, at a guess the new box will be able to see the recording files (though the box can read NTFS USB hard disks).