Witcher 2 had problems with performance at launch due to the DRM, and they remove it, so the DRM in Witcher 3, they also need to learn on installing it or not. I really hope i can play it on a single GTX680, because i'm not upgrading until next year, the 780 is not worth it because it's just a little cheap Titan, and the Titan is just a nerfed Tesla. Nvidia did a bad job messing with professionals cards and merging them into GeForce cards, which are meant for gaming only, and need to have a decent price, even for a high-end single gpu.
PS: And the 770 is just a 680 with +1000mhz on memory and some little bigger gpu clocks.