I found this quite useful. I have been using screen for a while but my friends use tmux. They love it and couldn't be bothered to switch to screen and me vice versa. Based on the post I don't seen any strong reason for either to switch unless there are other reasons not mentioned in the comparison.
Change the tmux keybinding from ctrl-b to ctrl-a and it will feel mostly like screen, but you will get all the extra tmux functionality.
> but you will get all the extra tmux functionality
That is what exactly? I stopped using screen a few months ago, tmux offers a set of default key bindings that are adjusted to modern software, a new biding for copy and paste (so you can control what machine gets the command), and... I still didn't find anything more that is relevant.
If he is used to screen, the key bindings will be more a problem than a solution¹, and the copy and paste thing is very niche. I don't think one has any good reason to migrate from one to the other. I did it to get to know tmux better, and really, that's exactly as much as I got.
1 - Unless you need to keep setting the bindings again and again.
For me, it is that I have a package like https://github.com/christoomey/vim-tmux-navigator
I can seamlessly move across splits in either vim or tmux without worrying which program started the splits.