I use the Poly variant by default, only disabling it in places where the monospacedness matters for layout purposes, e.g. the terminal recording in this article (because of Vim), and Rust compiler output in some of my other articles. The Poly variant does things like make i, l and space a little narrower, and m a little wider, which makes casual reading more comfortable than a strict monospaced font.
I do this because I believe that monospacedness is substantially overrated in most places, and that most things actually look better not strictly monospaced. I contemplated not even using a monospace-style font at all but decided that was probably going too far for most people. (And as a Vim user I necessarily work in a monospaced text editor; but if it weren’t for that, I’d probably go full proportional.)
So I’m curious if you have further feedback on this matter and why you find fault with what I’m doing. It may influence what I do.