You will have a far superior experience with a 7970 then you would with a 560Ti. With games using more then 2 gigabytes, a superior memory interface with the 7970 along with amount of speed that you would have over a 7970 it would be worth it however, that being said it may be wise to watch prices over the next couple of months leading up to the release of the newer cards.
Video cards were on the cheap during the holidays and now that the holidays are over the pricing has gone up. If you aren't in a hurry to buy it may be wise to watch the prices.
Here is a list of the 7970 and the Ghz edition cards from the lowest cost to the highest cost.http://pcpartpicker.com/parts/video-card/#sort=a5&qq=1&c=70,112