If you know all these things and you still can't tell that MWI is obviously true - a proposition far simpler than the argument for supporting SIAI - then we have here a question that is actually quite different from the one you seem to try to be presenting:

• I do not have sufficient g-factor to follow the detailed arguments on Less Wrong. What epistemic state is it rational for me to be in with respect to SIAI?

I respectfully disagree. I am someone who was convinced by your MWI explanations but even so I am not comfortable with outright associating reserved judgement with lack of g.

This is a subject that relies on an awful lot of crystalized knowledge about physics. For someone to come to a blog knowing only what they can recall of high school physics and be persuaded to accept a contrarian position on what is colloquially considered the most difficult part of science is a huge step.

The trickiest part is correctly accounting for meta-uncertainty. There are a lot of things that seem extremely obvious but turn out to be wrong. I would even suggest that the trustworthiness of someone's own thoughts is not always proportionate to g-factor. That leaves people with some situations where they need to trust social processes more than their own g. That may prompt them to go and explore the topic from various other sources until such time that they can trust that their confidence is not just naivety.