The claim that large EA donors are likely to return ≥15% annually, and plausibly 30%-100%, is incredibly optimistic. Why would we expect large EA donors to get so much higher returns on investment than everyone else, and why would such profitable opportunities still be funding-constrained? This is not a case where EA is aiming for something different from others; everyone is trying to maximize their monetary ROI with their investments.
Note that Scott himself has said he agrees the Libya intervention turned out poorly and is now no longer comfortable endorsing things similar interventions, see http://web.archive.org/web/20150731041537/https://slatestarscratchpad.tumblr.com/post/125060547081/how-have-your-political-positions-shifted-through
Dylan Matthews has read Superintelligence and wrote an article+interview with Bostrom about it in August 2014.
I think there's an error in your math. You're using log base 10 consistently in your article and the linked spreadsheet, but then you say the derivative of the function log(c)+k is 1/c. If you're using log base 10 throughout, the derivate is 1/(ln(10)*c). If you use log base e throughout, then each value you got for log_10(x) should be multiplied by ln(10) to get the value of ln(x). In either case, we end up with dollar amounts a bit over 2.3 times higher than your calculated values for the value of a marginal life in a pure aggregate utilitarian framework.
Also, nit: the Carl Shulman link is broken. You left off the http:// in the original link on your blog, so it was interpreted as a relative link, which was then copied over here.
Tom, can you clarify what the relationship is between the EA Hub and the EA Forum (If anything)? It seems like those links point at different things.