This belongs on the front page. Very well done.

I have never agreed with the Repugnant Conclusion, but I have always had trouble putting my disagreement into words. Your dialog makes several important points very clearly:

But don't say "having a high average utility." Say "use resources to increase the utility of people who already exist."

...

So "A+" differs from "A" both in the size of its population, and the amount of resources it has access to. Parfit was not "merely adding" people to the population. He was also adding resources.