This one has the GTX 870M, but no 3k display, so it's $300 cheaper.
The 3k display doesn't make much sense. It's a gaming laptop, but even with the powerful graphics cards in it, it isn't going to be able to game at 3k resolutions. It's just too much. A desktop even struggles with that sort of graphic intensity.
The GS70 is somewhat of an annoyance, too. The GS series is supposed to be compact and portable, but even if its the slimmest and lightest 17.3" laptop in the world, it's still clunky to lug around being that big.
I feel that the portability and higher end graphics card in the GS60 Ghost Pro-052 is the way to go. You get the best specs, the most portable machine, and don't have to pay for useless features like a 3k display that you can't game on.
Can't you adjust the resoluton though so for more demanding games you can just switch back to 1080p, and other games on 3K or less?
On mediocre settings, yes it can.
Keep in mind that an 870M on ultra settings in 1920x1080 on Metro: Last Light only performs at 34fps on average. You would have to be at medium or lower to play at a 3K resolution, so what is the point in cranking up the resolution if you have to knock the graphics down that hard?