You would probably be look at between 20-40% improvement depending on the game, and assuming no other bottle necks exist in your system, look at the bench marks from a number of different reviews to get an idea (don't just trust one sites results). As for if it's worth it, that's really your call. Also, people are expecting that eventually there will be a GTX 1080 Ti (there is no proof of this yet as far as I'm aware) so some people are waiting for that.
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