Hmm this sounds like a nifty idea : )
Can I ask a couple of things tho (being as I’m a noob at this!)

I can see the advantages using this over 4/5 separate copies, disk space, patching etc.. but could I ask what sort of advantages I could expect over just having them run from the same directory (as I do atm)?

Will it reduce disk activity too? And having this sort of system in place, will it reduce the load on your CPU?
Or is the aim exactly the opposite.. to increase the CPUs activity in loading up each WoW client by enabling the CPU to process the same physical file more then once? or allowing it to apply it to more then one Client?
(don't laugh :P I rly don't know anything about this sorta thing :P )

I.e. Faster loading, less strain on the disk, allowing the CPU to process more
Am I even close? :P