How really is FX better....

High ISO, you can compare yourself on this site.

DOF advantage for isolation is about 1 stop over DX

DR  Another big advantage over earlier generations such as the D200 / D300 but not the D7000

You can save money by buying F4 lenses instead of f2.8 and still come out with a performance advantage (assuming lens performance is equal). According to the new DXO lens numbers you can't buy a commonly available lens that will resolve much over 18mp. Even so the new sensors are still better than the older generation of 12mp sensors.

On the other hand you lose reach which can be very expensive when you go over 200mm.

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Sincerely
Ron J