I agree, and I think this analogy works: a company that sets out with the mission to "maximize shareholder value" probably won't maximize shareholder value. Most of the world's most valuable companies (that actually appear to have succeeded in maximizing shareholder value) have (fairly credibly) defined more meaningful missions. 

Hi Dan. I think GiveWell deserves credit for managing to move huge retail donor $s to evidence based causes, using their high-clarity, high-objectivity approach. 

Your approach at GivingGreen seems to test an interesting alternative. You encourage retail donors to give to climate change mitigation policy advocacy opportunities, which you perceive as higher expected impact than carbon offsets, yet offer recommendations on both. Clearly the policy angle is much more "complex" and can't be assessed without leaning on a bunch of assumptions about how politics & other complex systems work. 

But I think it remains to be seen if there is significant retail donor demand for this kind of advice. It's one thing to gain confidence in somebody analysis on a simple matter like mosquito nets, it's another to trust sombody's assumptions and world views about a complex matter like climate change mitigation policy advocacy.