It bothers me that this overloads the notation for repeating fractions. I guess there wouldn't be a use case requiring both in a single number, but you can imagine multiple numbers on the same page using this formatting for different purposes and it being confusing.

And it's fine for writing out by hand or in TeX (I assume), but good luck using it in any other context as we see here! Ideally a notation would be keyboard-friendly, at least for something with as wide an applicability as this anyway.

But this is certainly a good starting point.