It is worth it if the price is a lot better but you will not be maxing out all newer games with them. I have two r9270s overclocked (better than two 660s) and cant max out all of the new games on 1080p. I am not even sure if you could max all newer games with two 760s but you will get closer.
pfunkmd: He really doesn't need dual GPU setup to max most games at 1080P. Maybe you can't max out because of the dual AMD GPU crossfiring setup, which is plagued with problems.
AMD fixed the problems this is my second crossfire setup and the first had some problems but not as bad as what people make it out to be. I can max bf4 and crysis 3 but certain games like Arma 3 give me problems. Heck the 780 has problems getting high fps on some of the newer titles