Those are updated, new 12.8 drivers bring a big performance boost.
Check the latest 7970 review posted here for comparison...compare that to old 7970 reviews, there's a big improvement there. Also, the ghz edition at 1ghz start to beat nvidia's cards at those clocks.
Higher resolutions work best with a 7950/70 but a 670/80 is perfectly fine in the end.
I'd reccomend it if you want the absolute best, or you wanna bench with it. Other than that it's preference in the end.
For example, I bought a gtx670 ftw, instead of a 7970 cause it was a good deal. 7950's go for low prices nowadays, and so do the discounted ref 7970's you see here and there. (as low as $315)