It's personally more intuitive to navigate tabs using iterm and tmux just makes the screen space so limited. If I don't do pair programming is it recommended to just use iterm?
I like tmux because I can do everything without my hands leaving the keyboard. I vaguely recall trying iterm2.
Also, tmux is much like GNU screen. I can run a remote tmux session on a server, detach it, then ssh back in and get right back into that same session later (tmux && C-b D then tmux attach)
For now since I'm just working on a RoR app as a personal project, I don't really have a server and tmux's capabilities are limited on my end. So I might give tmux a go first and familiarise with it first, so i'd be more up to speed when it's capabilities can come to play fully :D
tmux really shines for me when starting or switching between projects. I can fire up a rails app with a single command and have all the tabs I like ready to go. Check out prag prog's tmux book for a quick intro: http://pragprog.com/book/bhtmux/tmux
Also, tmux is much like GNU screen. I can run a remote tmux session on a server, detach it, then ssh back in and get right back into that same session later (tmux && C-b D then tmux attach)