[udp]

27" at 2560x1440 is not high DPI and doesn't require UI upscaling. On e.g. a MacBook Retina you would not be able to read anything without upscaling because the pixel density is so high. It's the main reason I still use OS X on my MBP.

[MBCook]

For reference, a Retina 5K iMac is 27" and its native resolution is 5120x2880, exactly 4x as many pixels.

[theSpaceOctopus]

Thanks for the clarification.