I would really like to see VI emulation mode as well!
On the ESC Problem: Sublime Text does a good job of handling the ESC key. For example, if you have the find box active (i.e. if your cursor's in the find box) then ESC will exit the find box. If your cursors just in the code somewhere then ESC will exit vi's insert mode.
I realise that this application won't be able to do it the same, simply because it is a completely different application and environment. But there are definitely ways to make it work.
I would also be in favor of only using vi functionality over the pop-up find-replace, goto, etc. when vi mode is enabled.
Even something as basic as just the vi movement commands would be a great start in my opinion.