One nit, however: although I'm a touch typist (having learnt typing on a typewriter), I've long since trained myself to type the braces together and then cursor-left to fill in the details. This I do for ()'s, {}'s, []'s and <>'s; as well as quotes. Similarly I type the C-style /* * / comments as the pair of /'s first, cursor-left, then two *'s, cursor left and finally the comment text. It started out in this mode only when I wrote code, but now I find myself doing the same even with normal text.
Not sure how many there are like me (a senior early in my novice days showed me the practice and it stuck), but it always seemed like a simple way to ensure no dangling parens (assuming you're using "just an editor" like I do).
Could you allow for cursor-lefts to correct instead of just backspace?
To keep braces/quotes balanced, I've been using editor plugins like smartinput[1] and paredit[2] that automatically insert closing symbols. Even with the assistance, I've found it's easiest to continue typing through the closing symbols (as opposed to right arrowing).
The javascript is also less hairy without needing to handle typing braces together:)
[1] http://thechangelog.com/post/20172996073/vim-smartinput-smar... [2] http://emacswiki.org/emacs/ParEdit