GUI resolution: 1080p vs 2160p (4k)

Hi!

I have a general question regarding which resolution to choose for 4k TVs. I found this thread in the official Kodi forum: Should I configure Kodi with 2160p (4K) or 1080p resolution (upscaling)?
...where the recommendation from fritsch (kodi team member) is to use 1080p in the GUI and let Kodi switch to 2160p for appropriate movies.

I also found these recommendations for Nvidia shields which runs 4k: Recommended video settings for SPMC, NVIDIA Shield TV and UHD (4K) TVs with 4K GUI · koying/SPMC Wiki · GitHub
...where the recommendation is to set the GUI to 2160p.

I trust fritsch but the nerdy part of me wonders if there's been any progress in this area, or at least different for Libreelec? It would be nice to always output the highest possible resolution.

PS. My hardware is the newest Intel NUC: Intel® NUC Kit NUC7i3BNK

Quote from Klojum

Can most new 4K TV's do 4K@60fps these days?
Because having the Kodi GUI run at 30fps will look sluggish.
Hence, 1080p60 was favoured over 2160p30.

My TV (Samsung 55" KS9000) supports 60Hz in full resolution, but it's only possible if you have HDMI 2.0 or DP 1.2 which is still pretty rare for HTPCs. Older HDMI ports will only handle 30Hz which, as you say, feels very sluggish.