As you say, there may be people in OIT or the Nicholas school that have more insight than I do, but here are my thoughts.

Any server-based data storage option will be comparable whether it's on-site or off-site (Webfiles v. Mozy, for example). There could definitely be some variance in the relative efficiency of the servers at a given location, however.

Could anyone else provide any ideas about energy use in server versus local storage methods?