I'm interested.

While I don't have too much to add to this thread, I could show you this article by Dave Moulton.

As of recent, I found out my torso is actually quite short and I discovered that many bikes "recommended" for my height are way too large for me. I am about 5'9" with an inseam length of 87.5cm, or 34.5", which makes my torso small in comparison.

In my opinion, If you're in between size, it is the best to size down as you can fix the issue with a longer post, stem, more spacers and such.

Does my current frame fit me? No, but I make it work with a really short stem and it works for me.