At the moment, I can run native 4k at 50hz v-synced when I'm playing games with all the bells and whistles, and it's awesome. My circumstances: I've got a 1080 ti and a 50' Hisense 4k TV. The benefit being that you get most of the sharpness boost from a rez increase with a substantial reduction in performance cost, thus enabling 60fps/60hz, or a more consistent 60fps.
One of the takeaways was that it's possible to create an internal custom resolution of say 3200x1800 then have the GPU upscale that content to 4k. I was reading an article on Eurogamer about 'things PCs can learn from consoles regarding 4k content'.
