Remapping the caps lock key to the delete key (delete the character in front of the cursor) has been a great productivity boost for me. Below is the karabiner.json file that I'm using for this:
Interesting. Remapping it to Control is the greatest help for me because most Mac programs support basic Emacs keybindings. Using Ctrl a or e to go to the end of line is much easier than pressing Fn.
{ "profiles": [ { "name": "Default profile", "selected": true, "simple_modifications": { "caps_lock": "delete_forward" } } ] }