Everything I've read about Kepler tells me it's not nearly as good at compute tasks as the 500-series Fermi. For gaming it's awesome - like you said, better frame rates while using less power. But for everything else the 580 checks out better than Kepler.
In fact...to quote your own link:http://www.anandtech.com/show/5818/nvidia-geforce-gtx-670-review-feat-evga/15
"The GTX 680’s larger number of SMXes and higher clockspeed cause the GTX 670 to fall behind by 10%, performing worse than the GTX 570 or even the GTX 470
(emphasis mine). More so than any other test, this is the test that drives home the point that GK104 isn’t a strong compute GPU while AMD offers nothing short of incredible compute performance."
Too bad Adobe and AMD aren't on speaking terms...or we'd have seen the Adobe apps ported over to OpenCL years ago. As it is it's the green team for me.
all depends on what you need it for I guess