I just bought myself a PB287Q - 4K is
amazing. I'd say it's definitely worth the extra money - the 1440p PB28 iosn't exactly a cheap monitor either, so I figure if you're going to spend that much on a display, you may as well go all the way and pick up a 4K instead.
Just a heads-up: if you do decide to go with a 4K monitor, be sure your video card can output DisplayPort 1.2 - you can only push 30FPS over a single HDMI connection, and there will be an unacceptable amount of display lag at that. I had a GTX 760 that could
almost run everything I use at 4K, but have since upgraded to a GTX 980 which crushes everything, even gaming at ultra. It's effectively four 1080p panels - make sure you have the proper video hardware.
Just my opinion - take it for what it's worth.