3^^^3 dust specks in everybody's eye?

So basically we're talking about turning all sentient life into black holes, or torturing everybody?

I mean, it depends on how good the torture we're talking about is, and how long it will last. If it's permanent and unchanging, eventually people will get used to it/evolve past it and move on. If it's short-term, eventually people will get past it. So in either of those cases, torture is the obvious choice.

If, on the other hand, it's permanent and adaptive such that all life is completely and totally miserable for perpetuity, and there is nothing remotely good about living, oblivion seems the obvious choice.

This seems like a weird mishmash of other hypotheticals on the site, I'm not really seeing the point of parts of your scenario.

Well I personally don't want to be tortured, so I choose the dust speck.

Even if I wasn't personally involved, and I was to decide on morality alone rather than personal interest, average utilitarianism tells me that I should choose the dust speck. (Better that 100% of all people suffer from a dust speck, than 100% of all people suffer from torture)

This doesn't seem very coherent.

As it happens, a perfect and truthful predictor has declared that you will choose torture iff you are alone.

OK. Then that means if I choose torture, I am alone. If I choose the dust specks, I am not alone. I don't want to be tortured, and don't really care about 3 ^^^ 3 people getting dust specks in their eyes, even if they're all 'perfect copies of me'. I am not a perfect utilitarian.

A perfect utilitarian would choose torture though, because one person getting tortured is technically not as bad from a utilitarian point of view as 3 ^^^ 3 dust specks in eyes.