I'm significantly more productive with tmux + autossh. I autossh into a single server from which I have about 30 SSH sessions open - organized by environment (tmux sessions) and host (tmux windows). The windows have the name of the host. I rarely use my number keys - I just shift-left arrow or shift-right arrow to the previous/next window since jumping around is so quick.
tmux-resurrect is awesome too - if the server I autossh into reboots, I can just restore all my sessions and windows and it re-sshs into the 30 hosts.
I have almost this exact same setup, except I use tmuxinator instead of tmux-resurrect. Honestly tmux-resurrect looks like it's the better solution; I just haven't bothered trying it out.
tmux-resurrect is awesome too - if the server I autossh into reboots, I can just restore all my sessions and windows and it re-sshs into the 30 hosts.