There are now also two superforecaster forecasts about this:
Another historical point I'd like to make is that the common narrative about EA's recent "pivot to longtermism" seems mostly wrong to me, or at least more partial and gradual than it's often presented to be, because all four leading strands of EA — (1) neartermist human-focused stuff, mostly in the developing world, (2) animal welfare, (3) long-term future, and (4) meta — were all major themes in the movement since its relatively early days, including at the very first "EA Summit" in 2013 (see here), and IIRC for at least a few years before then.
What's his guess about how "% of humans enslaved (globally)" evolved over time? See e.g. my discussion here.
How many independent or semi-independent abolitionist movements were there around the world during the period of global abolition, vs. one big one that started with Quakers+Britain and then was spread around the world primarily by Europeans? (E.g. see footnote 82 here.)
Re: more neurons = more valenced consciousness, does the full report address the hidden qualia possibility? (I didn't notice it at a quick glance.) My sense was that people who argue for more neurons = more valenced consciousness are typically assuming hidden qualia, but your objections involving empirical studies are presumably assuming no hidden qualia.
Cool stuff. Do you only leverage prediction markets, or do you also leverage prediction polls (e.g. Metaculus)? My sense of the research so far is that they tend to be similarly accurate with similar numbers of predictors, with perhaps a slight edge for prediction polls.