Just a thought, seeing as how they used to make "field replace" drives for some of the Snap! servers: Has anyone considered that it might not be data on the hard drive at all that prevents you from swapping in other drives?
What I'm thinking is it might use a serial number or a certain drive identifier (i.e. when you boot drives on normal PC's, you can usually get them to respond with a model name like Maxtor 5T040H4 or some such) to restrict what kind of hard drives it will allow to be used.
Also, another thing which would help with all aspects of hacking Snaps: Quantum makes available for free their Snap OS to registered customers at
www.snapservers.com. The understanding of what lies in this would greatly assist any current or future hacking efforts. The two ideas I would have would be opening up the file and looking at it with a good editing program, or installing it over the network (I assume that would be the only way to install it to a Snap) through a packet sniffer to see what it passes to the Snap during installation.
Just a couple ideas from someone who would like to get into modifying Snaps in the future.