> Monospace is already such an awful layout for readability...

So why code in a monospaced font then? There's no rule that says you have to write code in a monospaced font. I've used proportional fonts for many years, and almost every programmer's editor supports them.

I'm currently using a slightly modified version of Trebuchet MS (I replaced the tilde with a better one). Another example is Input Sans, one of the three fonts today's thread is about.

If you like proportional fonts, go for it!