I basically do this, but I use "," (comma) as my leader, and I make capslock do double duty as ctrl and esc using KeyRemap4MacBook (<a href="https://pqrs.org/macosx/keyremap4macbook/" rel="nofollow">https://pqrs.org/macosx/keyremap4macbook/</a>). The trick is first remap capslock to Ctrl in keyboard system preferences, then use KR4MB to remap Control_L (the left control key, which is to say, what capslock now signals) to Control_L, but if you type ONLY Ctrl_L it sends esc. so when i need escape, it sends that. when i want to use it for Ctrl-modified combos, it does that. Works fantastically for Vim, i've been doing this for a couple years now. Also nice for emacs keyboard shortcuts in other apps that respond to them.