Much to my surprise, after I was forced by circumstances to use Ctrl+[ for a month or so, I found I didn't actually want to go back to Esc.

Had it only been a week or two I suspect my muscle memory wouldn't've shifted though.

And vi too - works just fine, but you have a valid point about muscle memory, which is pretty much the only kind of memory many of us have left when it comes to vi-like editors, since the key sequences disappeared from our brains decades ago!