This is awesome and has opened my eyes to features of emacs I didn't know about. But I still have use for tmux because it lets me attach to the same long-running session on a remote host from multiple clients. I'll probably just start having emacs be the only window open in my tmux session.
I use emacs every day. You'll soon find emacs is a terrible xterm/gnome-term/iterm/whatever-term.
* The emacs terminal is very slow. Run a command that produces a few hundred lines of output and you need to wait 30 seconds for it to catch up. A dedicated terminal program displays the output several orders of magnitude faster.
* Emacs crashes or freezes from time to time forcing you to kill all your emacs terminals anyway. It isn't nearly as stable as tmux.
That said you can connect to a tmux session with an emacs terminal. That fixes the stability issue - even if emacs crashes your tmux session lives on. It doesn't handle resizing well, and it is still slow as molasses.
I do use emacs server. That plus emacsclient allows you to open files instantly, and your term mode and gui mode emacs can share buffers.
