I had a 560Ti for 3 months and sold mine for a loss of $30. I didn't mind cuz I used it for a couple months. I sold it to a friend and it had warranty still.
If you are doubting and wanting more, then upgrade. I splurged to a 660Ti. Mind you I went from 560ti to 660ti. I love the boost, but it depends on what you want to get out of your GPU. At 1080p it plays what I want at great speeds and quality. If you bought a 660ti you'd be impressed.
The 660ti price is high. I completely agree with people that say it should be lower, like $270 or so. It could drop in price, but if your willing to spend $300-320, then consider a 7950.
Going solely on performance and/or temps, the Gigabyte is the better card. I've owned 2 now, one of my old 560Ti's and now my 7950. But if you are even slightly concerned about the future(failures) EVGA has better RMA options.
Strange... There you find 660 beating 7870. I'm sure in the beginning (at 660 launch), techpowerup has the 7870 faster. But anyway, Reference 7870 are cheaper than that. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Overclcok it to1200 MHz and it will beat the 660, even the Hawk.