I'm looking for an external thunderbolt drive to back up my Mac Mini. The mini has a 1 tb drive and currently uses about 600 gb. I could save a lot of money by purchasing a 1tb backup drive. But I figure I should go for at least 2 tb, just to have the extra space if necessary. However, is there any benefit to getting a larger, say 4 TB drive? They're expensive, and I don't think I'll need that much storage any time soon. And, there's a risk that by the time I need that much storage, any drive I buy today will be outdated. Your thoughts? Any suggestions for a good thunderbolt drive? (I've had mixed experiences with WD drives.) Thanks in advance.