I'm a long-time screen user, and I recently switched to tmux purely because it seems to handle high-color and unicode more cleanly than screen. I configured it to completely replicate my screen setup so that I didn't have to learn anything.
e.g., in screen I could configure "^a j p" to do one command and "^a j d" to for another:
> bind j command -c foo
> # CMD KEY NAME CMD
> bind -c foo p screen -t '% |db' make db
> bind -c foo d screen -t '% |prod' ssh prod
If that's possible, I'd love to know how. It's what stopped me from switching a few months ago, and is now the most painful change after switching again a couple days ago.