The guys at Tech Power Up have tested a pair of GTX 1080 in SLI using the new HB bridge.
http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_1080_SLI/1.html
Unless you game on a 4K or an ultrawide monitor, going SLI is not worth it. Oh, and the new SLI bridge is useless.
Please excuse my bad English.
Currently gaming on a PC with an i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.