After a quick glance this looks pretty useful for me. I'm the kind of guy who is willing to change words or sentences (up to a point) to make the overall text look prettier.
I also do this for monospace text, but in proportional there's perfect "fill" justification which for some reason gets ignored.
Here's how you do it in advanced layout systems like CSS: https://stackoverflow.com/questions/6205109/justify-text-to-...