[madars]

I have zero issues with HiDPI on Ubuntu + xmonad set-ups. In particular, setting xrdb's Xft.dpi to a good value (e.g. 144, an "even" multiple of 96 for X1 Carbon) seems to work well. However, I mostly use my laptop for Chrome, emacs, and terminal, so YMMV. HiDPI screen is definitely worth it for your eyes.

[nixpulvis]

Do you use external monitors that have different resolutions?

[madars]

No. Unfortunately, I can't say good things about differing-display support in Linux. For example, even if DPI is matched but one of the monitors is rotated (my old setup), freetype anti-aliasing settings are still global and can't account for rotation :( This matters less with HiDPI, though.

Fortunately, Dell U2718Q's are relatively cheap and well-worth the upgrade :)