I've had my caps lock key mapped to the control key for the last few months as I have migrated back to Emacs from TextMate. It was a slight improvement over the placement of the control key but not a huge improvement. I came across this article: A Useful CAPS-Lock Key from Brett Terpstra and decided to give his mapping a try. This mapping requires free third party software, but I was particularly intrigued not by the escape key mapping, which is very handy, but by the "Hyper-key" (ctrl-shift-cmd-opt) being mapped to holding down the shift key. This opens a lot of potential system wide shortcut key-bindings that are a lot easier than using the uncomfortable ctrl-shift-cmd-opt.
So far it is very useful, I like the hyper-t for opening iTerm2 in visor mode, very handy. I will check back in in a month on this topic and share any other key bindings I come up with.