4K monitors

Sometime before the end of the year I will be getting a 4k monitor. I'm mainly looking at the upcoming Asus 32in Pro Art series and another person mentioned on another forum the BenQ BL3201PH. One hot button issue with a lot of the IPS 4k monitors is input lag. I currently have a Dell U3011 30in 2560X1600 monitor(which many have said was "terrible" for gaming) and I don't notice any input lag personally, even when playing CSGO. We don't really know what the upcoming Pro Art series monitor will be in that regard but I would think it would be a tad bit better than Asus's current 32in, What's your personal take on input lag of Asus's current 32in 4k and the BenQ and how much of a real world difference is input lag in general?

We got a 4k Dell monitor a few months and I didn't notice any input lag whatsoever however it was capped at 30fps. I would get a good 1440p monitor. I much prefer my 1080p 60fps monitor in comparison.

Yeah, the only 4k monitors I'm interested in is 60hz IPS panels. I already have a 1600p panel and wouldn't get a 1440p panel unless I wanted higher refresh rate.