I honestly don't expect a lot from the HD6000 series. I mean, probably like going from the 8800's to the 9800s, give or take a little.
However, if I can get a 6770, that has, say the performance of the 5830, for about $130... why not? Would be a neat little upgrade from my 5770. Not much, but something.
Or, with the drop in price of the GTX460, I can get a decent boost in performance.
Either way, them competing is great for us consumers.