wedrifid - Thanks for your kind remarks. As I said in my top level post, I'll be taking a long break from LW. As a brief answer to your question:

(a) I think that Eliezer has inspired people (including myself) to think more about existential risk and that this will lower existential risk. I thank Eliezer for this.

(b) I think that Less Wrong has provided a useful venue for smart people (of a certain kind) to network and find friends and that this too will lower existential risk.

(c) Most of what I know about the good things that SIAI has done on an institutional level are from Carl Shulman. You might like to ask him for more information.