I work as a video editor for a company, and we just bought some 5k iMacs. Now we are looking to replace secondary monitors with 4k. Are there real advantages for a 4k computer monitor over a 4k TV? The difference in price is quite dramatic.
A 4K monitor isn't going to have any of the image processing algorithms your typical TV will have in order to make the picture "look better". You don't notice the delay with non-interactive content, but it's varies widely on televisions and will be exaggerated on a dual-monitor setup (one display will appear more responsive than the other).
I'd recommend either the Dell P2415Q or P2715Q as a secondary 4K display.