4K at 27" would still be considerably lower pixel density (~160 ppi) than my old Motorola Atrix phone (275 ppi), which had lower density than my current HTC Rez

4K at 27" would still be considerably lower pixel density (~160 ppi) than my old Motorola Atrix phone (275 ppi), which had lower density than my current HTC Rezound (342 ppi). I found the difference between the Rezound and the Atrix to be striking, so I think 4K at 27" would not be overkill by any means at half the density of the Rezound, even taking into account that the display will be a little farther from your eyes.