Incredibly frustrating. I have trouble when I have to use other PCs or devices. I can no longer use the "arrow keys" and get momentarily confused when hjkl are showing up in the textarea instead of giving me movement. And I can't tell you how many times I hit escape in LibreOffice/Calc/etc.
This is one reason why I don't use online editors like Google Docs. They don't have great vim keybindings. Even extensions like Vrome and Vimperator fall just a little short. And for apps that do have a subset of the bindings--they are almost worse than having no bindings at all; evince has hjkl, but no gg/G, etc. It drives me mad.
I've configured AwesomeWM to be vim-like, but how I wish there was window toolkit-level support for vim bindings! In fact, I wish I could run everything from vim.
QuickCursor on OSX does basically that in just about everything... (like this post)
It's not free (bummer) but it lets you take just about any text input area and by some clipboard trickery fire it up in your favorite editor (macvim being one of the defaults, but not limited to that) then writing back to that field when you exit/save.
So you can quite literally edit in your editor of choice, 100% in the environment you want.... pretty much what you just asked for right?
(Basically it's just cutting/pasting and opening applications in an automated way rather than have you do it - but bind it to a friendly key and you're good to go.)
Vimperator/Pentadactyl are not really editors, but they are awesome if nothing because of Ctrl+I : it opens the current textarea in GVim, and then you just need to save & exit and the contents are automatically loaded back.