My great wife purchased an EVGA GTX 980 TI Hybrid for me and I have been using it for the past two weeks now and I have reinstalled my SLI GTX 780 TI Classifieds (Classified and a Classified Kingpin). I game on a Dell U3415W (3440 X 1440) with an I7 4790K CPU.  I am thinking of staying with the SLI 780’s over the Hybrid. I enjoy the lower heat signature of the Hybrid over the SLI 780 TI’s. I am using a HAF X case so space is not an issue with either GPU. I mostly play BF4 and other games (Witcher 3, GTA V, Batman Arkham Knight) occasionally. The only issue with the 780 TI’s is playing Batman Arkham Knight the video card driver will stop responding and restore however it will close the game. With the Hybrid no issues with playing the game.  On side note I advertised my 780’s on Craiglist for $600 and not one email or call. The 780 TI’s where purchased from Newegg and Tiger Direct and are registered with EVGA. What are other members thoughts on keeping the 780 TI’s over the 980 TI Hybrid? 

I would never take one 980ti for 780ti sli myself. I haven't checked, but I assume sli 780ti's, trounce a single 980ti in 3dMark. I feel you on the scaling issues with sli, but that's not a good enough reason. The extra vram is the only area that is an upgrade.
Now if you can swing another 980ti into the mix in the future, that would certainly swing my opinion.