Checking in the store is always a great option.
It takes quite a bit or horsepower to run 4k for games.
Most if not all 4k monitors can do 4 pixel upscaling of 1080p avoiding the blurring(4 pixels would be used for every 1080 pixel) of running a a different resolution.
For video and photo editing it may be nice to have more room for tools and even input/output video windows(but this can also be done on dual screen or ultra widescreen setups).
I personally do not have much interest in 4k or ultra HD outside of videos because the Internet is certainly not 4k ready since most websites do not even fill a 1920 x 1080 screen(this website is only about 1410pixels wide). This leads to using scaling or zoom. Some sites scale well(vector images and a good content system) while others do not(raster images that are not big enough and get blurry).
This website adjusts to resolutions fairly well(The main logo is a vector type image so it scales well). User avatars do not and all the text clearly will scale perfect on almost any website.
Since you list 2560 x 1440 here are some examples of a site that takes advantage
These images are very compressed, bit is more to give an idea of monitor space use. Multiple programs work great on high resolution screens. Remember more pixels in the same size are smaller pixels so for 4k I recommend getting a larger screen. 2560 x 1440(1440p) is good for most users at 27-32 inches. but each user is different.
It was at 110%, my bad either way it has so much info it can use higher resolution screens with less scrolling
http://i61.tinypic.com/2ex3gxl.jpg
Here is something that does not at all.
http://i59.tinypic.com/14buj41.jpg
This is this forum
http://i58.tinypic.com/2s98475.jpg
Anandtech
http://i58.tinypic.com/zxtg83.jpg
Overclock.net
http://i57.tinypic.com/1z18z1j.jpg
Here are some scaled images(150%)
http://i57.tinypic.com/e5ky91.jpg
We scale pretty good
http://i58.tinypic.com/2czy52p.jpg
http://i58.tinypic.com/5dl99h.jpg
http://i60.tinypic.com/2utg23b.jpg
I can get you some better crops to show you how the scaling looks on images. just ask.