In the *nix world, when something gets abandoned people are pretty quick to move on. I've been using tmux for a long time as well and see no need to even consider going back to screen.
Thankfully though, I can have both screen and tmux on my machine, so may day-to-day tool is tmux and screen gets used whenever I need a time machine (which still happens at times)
A quick
screen /dev/ttyS0 115200
Keep in mind that this could be related to the default minicom config my distro shipped back when I was "evaluating" my options, but because screen works totally well for my cases, I've had since zero motivation to go back and give minicom another try.
picocom -b 115200 /dev/ttyS0