Well, I can give you some feedback from my config. You might be a bit surprise though. So I have a Sager, 17" with a I7 4910MQ clock at 3.99ghz with 16gigs of Ram and a sli of 780m nvidia graphic cards. Now here's where it gets tricky:
-My first 780m (4gigs) is overclocked to 1034mhz with a voltage clock to +75mv
-The second 780m is overclocked to 1070mhz with a v clock to +100mv.
With this config I can run the game in the open world section with 35 to 45fps, everything Ultra, even hairworks, minus AA at 1080p (Tried 4k downscale, I was between, 15 to 25fps unplayable but surprisingly high for max out, maybe with hairworks off I could play lock to 30fps, I'll try to see if it's possible).
At 1080p, the worst deeps I can get occur during cinematics, down to 29. Other than that I'm the happiest gamer on earth. Still waiting for the terrain setting to be fixed though. I want to see how Tesselation looks ^^.
Other than that, amazing game thank you CDProjekt!