Bought a 980 for my birthday, had a perfectly good 780ti at the time. I "kinda" justified it by having just bought a 144hz Gsync screen. I do get satisfaction that I know i am running games to the best of my ability for the budget I have, Titan money is out of my reach realistically without further justification which even with my man maths I can't reach!
780 ti to a 980!?
Man, talk about an incremental upgrade...probably all you noticed to begin with was quieter fans...
Bit more of a performance gap between them now, but that is only because Nvidia have let the driver support slip (and no doubt totally intentionally as well.....scumbag company).
Had you saved your Geld, then you may be in a position to get 'almost a Titan' now in the form of the GTX 980 ti. That would be a bit more like an upgrade that you wouldn't have to check the driver signatures to be sure you had. Even then, I personally prefer 100% + performance gains when I splash the cash for an upgrade, which I expect to get when I go from my HD 7970 to the GTX 980 ti hybrid....
Playing Witcher 3 on my laptop (GTX 980M) just now, which actually gives better gaming performance than my HD 7970. Crazy the amount of performance that they can squeeze into laptops these days...but yeah....if my laptop is beating my desktop, then I *need* a new GPU.....and at least I amn't spending on it on crack.