Hmmmm, do you really need it? I mean I guess you would get around 150-200 from the card. I guess you run at 1080p, if you run higher then the 980ti is much better. Have a look at this
Its up to you in the end, but there is a big performance increase, but I don't know if its worth the money.
I did almost buy a second 980 and sli it. I dont think Ill have any heat probs as Im liquid cooled. I should probably make this decision when my wife is around............