Start here:
- Utilitarianism.net (MacAskill and Meissner, 2020)
- The golden rule (Paul Christiano)
- Report on Consciousness and Moral Patienthood (Luke Muehlhauser, 2017)
Further reading:
- How to be a consequentialist about everything (Toby Ord)
- The Hedonistic Imperative (David Pearce)
- Why I don’t focus on the hedonistic imperative (Brian Tomasik)
- Utilitarianism, contractualism, and self-sacrifice (Carl Shulman)
- Valence eliminativism (Phil Trammell, 2019)
- Is brain size morally relevant? (Brian Tomasik)
- Which computations do I care about? (Brian Tomasik)
I would add the extended episode of the 80,000 Hours podcast with David Chalmers. To my knowledge, some of the views he expresses there—e.g. that phenomenal consciousness is morally valuable even if not hedonically valenced—have not been explicitly discussed in either the EA or the philosophical literature.
Many utilitarian EAs have independently gravitated towards the view that the intrinsic value of pleasure and pain can be known by introspection or "direct acquaintance". Surprisingly, as far as I know no statement of this view exists in the EA literature, though some may be found in the philosophical literature (including publications by philosophers sympathetic to EA):
I also noticed this when I started planning a blogpost on this topic!
De Lazari-Radek and Singer's The Point of View of the Universe has a chapter on hedonism, but I think the argument is less developed than in the two links you give. (BTW, if you have a copy of the paper by Adam Lerner and think it's okay to share it with me, I'd be very interested!)
It's interesting to note that Sinhababu's epistemic argument for hedonism explicitly relies on the premise "moral realism is true." Without that premise, the argument would be less forceful (what remains would be the comparison that pleasure's goodness is similar to the brigthness of the color "lemon yellow" – but that doesn't seem to support the strong version of the claim "pleasure is good.")
Also Rethink Priorities: