That's still 3 extra key strokes, including a key combination, to go from writing the constant name back to writing the next word (with caps lock: caps lock, constant_name, caps lock; without caps lock: constant_name, Esc, g, shift+u, b, i - you also need w, i to get back to the end of CONSTANT_NAME and keep typing). Also, switching mode, applying a command, then switching mode again versus pressing a key for uppercase and pressing it again for lowercase is a much bigger distraction from my point of view (emacs user) but maybe you actually get used to that using vim.