To add to your list of various alternatives... My personal skepticism re SI is the apparent lack of any kind of "Friendly AI roadmap", or at least nothing that I could easily find on the SI site or here. (Could be my sub-par search skills, of course.)
Apparently they are figuring out that roadmap, a problem with any research, even non-academic ones. I assume the sub-topics discussed so far are central points in question, but if SI keep in secret some insights, well, it's for the sake of security, or lack of transparency. In some cases, people bothers to much about the institution.
Related Posts: A cynical explanation for why rationalists worry about FAI, A belief propagation graph
Lately I've been pondering the fact that while there are many critics of SIAI and its plan to form a team to build FAI, few of us seem to agree on what SIAI or we should do instead. Here are some of the alternative suggestions offered so far: