I recently ran into a bunch of problems running neovim under GNU Screen with `TERM=screen.xterm-256color`. There was some kind of problem relating to GNU Screen's parsing and re-transmit of certain full-color terminal escape codes. I don't remember the details right now, but what I know is that building the latest from source didn't help. (I wish I could remember the specific issues)

Same - I'm at about 20 years give or take.

It also has every feature known to exist in this space.

I agree though that the world is moving in the way of tmux - I'll get around to switching occasionally.