Taskwarrior dev here.

When we receive feature requests, it's more likely that the response is "please tell us more", than "uh, tl;dr, could you make a pull request, thx". Particularly as we don't work from pull requests. In fact, I feel like we spend all our time asking for more details from both feature requests and bug reports.

But I like your idea, and I wish you had made that feature request. This seems like an interesting improvement to urgency, and anything that truly improves the handling of lists is fair game.

I like the non-linear ramp up as the due date approaches. Do you cap the number? Otherwise it seems that other urgency factors will be drowned out.

I agree about the "Estimate progress", which is only prone to manipulation as you said, but also omission. Any data that is collected, and simply shown back to the user isn't really pulling it's own weight.