Currently, I have one LG 5K ultrafine monitor and two planar ix2790.
All planar ix2790 monitors, which I've tested, are built with defective panels from iMac 27" 5K.
Those two I own have dead pixels and ghost image across border.
Also, I've tried Iiyama 5K monitor - they also built from defective iMac 27" 5K panels and have a lot of dead pixels.
The first LG 5K, which I've bought, have ghosting across the entire screen - it's impossible to use such monitor - I've sold it for parts.
Second LG 5K I've bought was fine - without dead pixels and other defects.
But three years passed, and now I see ghosting across border of screen.
So quality of this LG-made 5K panels is not very good.
As I see these Kuycon g27p monitors are also built from LG 5K panels.