According to Apple's math for "Retina", phones are held at 10" and you need 330ppi like an iPhone. But laptop screens are used at 16" and only need 220ppi like the new Retina MacBooks. So if you use a monitor at a distance of 30" (which is more likely if you use a huge 27" monitor) then you only need about 120ppi to have the same angular resolution. I've seen one of those Korean monitors, and they're definitely dense enough that you need to increase the size of elements on the display. That means pixelization unless you use high-res assets.