I love XFCE but I've had a hell of a time getting it to work nicely with multiple high DPI monitors. I finally gave up and went to KDE which.. just works.
Unfortunate because the minimalism of XFCE is way more my style.
Yep. Unless you have really good eyes, XFCE is unusable on a 4K screen. On the same screen, KDE at 150-175% is glorious at providing both more real estate than 1920x1080 while being crispy.