Well, I guess I'm an a-typical reader - although quite voracious -
since I do notice the grammar, the punctuation, et.al.
If the difference is between one space and two spaces, I agree that is very noticeable.
But, what Jury is advocating is using something slightly smaller than one word space. So, if the difference is between one space and something slightly smaller than one space, I doubt *that* would be noticeable. I don't believe I would notice it, but I will confess that your powers of observation may be better than mine.
I have to wonder how many professionally published books go as far as Jury suggests. It seems to me that most would consider it overkill and too much effort. My guess is that most of them are satisfied with one space between sentences, which I trust you have observed in your voracious reading.
Virgil