"Wouldn’t it be nice if someone came up with an inexpensive alternative that wasn’t a full-face unit?"
Having had a few bite tabs break over the years having to hold the reg in my mouth for the return swim is not my idea of fun!
I’ve gone the other route and use a SeaCure which is not inexpensive but fills the mouth and probably wouldn’t come out if I passed out but you don’t need to bite on it the whole dive either.