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This is actually what I do, I have a gigabit NAS for the raws themselves. When I come back from shooting, I dump the files onto the NAS, and the import them into LR4 from there. LR4 catalog is stored locally, but backed up to the NAS.
I actually don't rely on the LR4 catalog at all long-term. When I'm done with a directory of files (each corresponds to a day of shooting or a specific event I shot at), I save all the XMPs to the NAS also (in the same directory).
The benefits of this setup are that I can use different computers to edit or postprocess files on the NAS at the same time, though not using the same directory at the same time, and the NAS is independent of the individual computers.
Don't forget to back up your NAS because even if it is RAID, it can still fail. I also use a NAS that can be locked and unlock, the only time I need to unlock it is when I copy new files to it or when I save the XMPs and catalog files to it (all the rest of the time the NAS is read-only).