That was my problem with tmux. I don't really care for vsplit (and could've had that with screen patches), so feature-wise there's no big difference. Some version of screen is often pre-installed on servers, so that's probably my first choice when it comes to situations where running things in the background is my prime motivation. For multiplexing on my home system that's not an issue, so both would be fine.
I recently started trying out tmux for that purpose as someone told me its memory usage wasn't as creeping. Can't really detect a big difference, though, after a while both of them take up a few hundred megs.
Not close to the vim vs. emacs holy war level. More like emacs vs. xemacs.
Or did I miss some hidden gems of either of them?