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I'd say 3 tb fusion, buy a thunderbolt enclosure, and get a 1tb ssd in the future.

Right now 1tb ssds are $600 and dropping fast.

There's two current $600 1tb ssd's on the market and this is the best:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820147251

The other is a corsair m4.

These prices are dropping fast, and a thunderbolt drive would make sure it performs as fast as it does. A fusion drive would make sure your 3 tb performs good.
 
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