I don't think I've ever seen evidence that emacs users actually need to be very productive in their text editor even if it works.
Though it might not work - the original Mac user research found that keyboards make users think they're faster, but don't actually make them faster, because of time blindness.
I wouldn't know. I'm a vi user. I don't know how much more productive I am with VI than non-modal editors, and even if I did know that would just be anecdotal, but I feel more productive coding in (Neo)vi(m) than I do in any non-modal editor, and it's much more comfortable anyways.
Though it might not work - the original Mac user research found that keyboards make users think they're faster, but don't actually make them faster, because of time blindness.