the creation of people is a complex moral decision
True enough. But it seems to me that hesitation in such cases is usually because of uncertainty either about whether the new people would really have good lives or about their effect on others around them. In the scenarios I described, everyone involved gets a good life when ask their interactions with others are taken into account. So yeah, creating livres is complex, but I don't see that that invalidates my question at all.
preferences, not happiness
That happens to be my, er, preference too. I think I do think it's a nitpick; we can just take "10x happier" as a sort of shorthand for some corresponding statement about preferences.
designed to confuse the moral intuition
I promise I had absolutely no such intention. I took the levels higher than typical ones in our world to avoid distracting digressions about whether the typical life in our world is in fact better than nothing. (Note that this isn't the same question as whether it's worth continuing such a life once it's already in progress.)
Your example of a world half as happy as this seems like it has a similar but opposite problem: depending on what "half as happy" actually means, you might be describing a change that would be rejected by total utilitarianism as well as average. That's the problem I was trying to avoid.
You're given the option to torture everyone in the universe, or inflict a dust speck on everyone in the universe. Either you are the only one in the universe, or there are 3^^^3 perfect copies of you (far enough apart that you will never meet.) In the latter case, all copies of you are chosen, and all make the same choice. (Edit: if they choose specks, each person gets one dust speck. This was not meant to be ambiguous.)
As it happens, a perfect and truthful predictor has declared that you will choose torture iff you are alone.
What do you do?
How does your answer change if the predictor made the copies of you conditional on their prediction?
How does your answer change if, in addition to that, you're told you are the original?