I found this a bit dense; I think that you could say what you wanted to say more concisely and relegate the integrals, math etc to a footnote.

I think that the essential point is that the universe is a damn big place, full of energy and matter and ways to use it to produce gazillions of highly-optimized, pleasurable, worthwhile (post)human lives.

Therefore, if you are an aggregative consequentialist who sums up the utility of each individual life without really aggressive time-discounting, a small reduction in existential risk creates a massive increase in expected utility.

The summary is good. I'd like to hear a bit more analysis of what it actually feels like to have that weight on one's shoulders and how to deal with the scope insensitivty. Also, one should question the aggregative assumption. Does it really capture our intuition? How does this all relate to Pascal's Mugging?

I'm a fan of your blog too!