Mantle is really the missing puzzle of what the PC Game performance lack compared to console. Once every game is mantle ready, the vision of one unify gaming platform is less opaque and couldn't be more happy that vavle constantly advocate it with steamOS that based on debian. We're no longer locked down to specific platform in few years time if everything is going as plan and proceed with seamless transition.
I believe in few years time we can build a more powerful pc that can be much more portable than ps4/X1. The Mac Pro is really a great example of how far we can tweak it to create a better gaming hardware in such a small size.
well atm the performanrce of high klevel gfx cards is kike trhose runign on AMD cou hardware, and the 58% on xfire i thin is due t th fct you dont have memory copyng, instead of having 4GB in 2x 290 you have 8GB cus its hardware agnstic and can utilise it all, not sure typin is crap cus ive got hiccups bt think its along those lines