And I still believe the best comparison to the 780ti will come with the release of the 980ti.
But for right now, does it make sense to dump your 780xx in favor of a 980? Probably not so much. But if you need a new top end card for a system and can get either a leftover 780xx or a 980, it's the 980 hands down.
Then there are those of us who are still getting good use out of their 660ti. I do not plan on upgrading for at least another year or so. This will be about the time I will be ready to build a new system.