I went with the i7 model, which has the 2TB HDD.
It does come in i3, i5 and i7 flavors though.
I moved flat recently and haven't got the space for my 27" Mac so I sold that and thought I'd treat myself to the more expensive Alpha with the money.
With my Mac I mostly booted into Windows for Steam anyway, using the OSX for my Photoshop work, so the Alphas custom UI seemed a good choice for my usage