I'm just getting back into programming as a retirement hobby after leaving the field due to burnout 15 years ago. That means I'm only just starting to figure out editors and such.

I don't know of any code editors that use tab stops the way a word processor does. A word processor uses tab stops specifically for alignment at defined positions rather than tab characters equivalent to specific number of spaces (or tab key to insert specific number of spaces). Without the ability to set positional tab stops, I don't know that proportional fonts will be all that great for most people.

I took a look at your link to almost proportional fonts. Thanks. I don't know how I missed that, given that iA Writer is one of the editors I've been playing with for general purpose writing. (I've become disillusioned with the state of modern word processors.)