The 5870 has turned out to be ridiculously futureproof which is complete luck on my part as I almost went for a lower end, newer generation 6xxx which was more expensive. Turns out the 5870 has destroyed a lot of the competition for a long time.
Yea the 6xxx was made to use less power and shit. They arent any better than 5xxx.
Happy with it too, only bought it for bitcoin mining, didn't know it was so damn good.