Multiplication does plenty of good. Pretend instead of an infinite time it's a finite time, X after everything else. Make the decision you would make in the limit as X -> infinity.
As for tradeoff rates between torture/happiness, it depends to some extent on the individual. There are cases where I would let someone live (because I thought that was the right thing to do, not because of intuitive deontological constraints) who wanted to risk torture, while I myself would commit suicide. I just wouldn't let people risk torture because of time discounting, or because they refused to imagine how bad it would be.
As for my own tradeoff rate, it's not something I can report without deep introspection, Fermi estimates of how bad torture could be and how good "happy fun time" could be, and binary searching with thought experiments to find which I would prefer, which I don't have time for now.
There is epsilon chance of "infinite bad time" and ~100% chance of finite benefit if you make choice A. If you instead make choice B there is 80% of "infinite bad time" and 20% chance of 10x the finite benefits.
Clearly, you should take course B, because it's -infinity +10/5 instead of -infinity +1
EDIT: I was originally referring to multiplying a finite probability by an infinite negative.
I recently published Mortal, a novella-length My Little Pony fanfiction meant to introduce anti-death concepts to an unfamiliar audience. Short description:
This is a character-driven melodrama. It's not particularly rationalist, but it's very, very transhumanist. Unlike, say, Friendship is Optimal, I wouldn't necessarily recommend this one to people who don't already know the source. It assumes familiarity with the characters and the world.
I am going to talk about how I put together the story and how people reacted to it. This will contain spoilers.
This line exists so you can break out of the automatic "read everything on the page" mode if you want to avoid the spoilers.
This story was structured as something of a bait-and-switch. I watched the reaction to a previous transhumanist horsefic (yes, there's more than one), and I was struck by how easily readers matched the explicitly anti-death narrative to the "immortality is a curse" trope. Rather than fight against this trend, I decided to work with it. The first act is meant to look like a story about learning to accept the inevitability of death. Starting in chapter 3, I break further and further away from that mold until the protagonists finally rebel against the status quo.
The first chapters got a lot of people invested who I suspect would've been turned off by a less familiar opening. Once I was into the third act, I stopped being subtle and used every trick in the book to make the pro-death characters look like the unreasonable ones. Judging by the comments, there's no shortage of readers who were angry at having their expectations flouted, but quite a few seem thoughtful, and some explicitly changed their mind on the subject.