Can you elaborate on why you prefer tmux? Myself, I use byobu, a set of user-friendly wrapper scripts around screen.
http://unix.stackexchange.com/questions/549/tmux-vs-gnu-scre...
In particular, when i've played with screen, i found that i was frequently stymied by the broken abstraction of the way screen stored its state vs what I wanted to do.
byobu sadly doesn't work on macbooks, but it looks cool!
http://www.linuxized.com/2010/05/switching-from-gnu-screen-t...
Plus the more liberal BSD license but that's more of an ideological issue.