When I ordered a new laptop at work, I asked for a 4k screen. My reasoning was the higher pixel density would make for a sharper image for my aging eyes and Windows will let me set a scale factor. Well, yes, Windows will let me set a scale factor but the number of applications, even new applications, that take scale factor into account is disturbingly low. My current scaling on the 4k screen is 250% which gives me close to the amount of information you would see on a 1920x1080 screen. It's a beautiful and very sharp display, but here is what I found.
o Many applications applications only take into account the screen resolution and scaling of the main screen and when moving screens to another monitor (ie 1920x1080) does not cause the application to adjust it's scaling.
o Some applications become unusable. The first time I used SQL Prompt on this laptop, I could not see all the options on Edit Styles screen. Redgate was very responsive when I talked with support and this was fixed relatively quickly. Other companies responses to similar bug reports are, well, lacking in comparison.
o Some applications only scale parts of their screen but not others making it look very strange and hard to work with.
As much as I love the sharpness and color on this display, I would never get another 4k screen on a laptop. They're great if you under 30 and don't need to use scaling but it's been far too much of an annoyance using it with a scaling factor.