One thing to gain from rationality, apart from what you mentioned, is a firmer understanding (and real belief) in reductionism. This can apply to pretty much anything, and I think for me contributed to a new understanding of consciousness. On the topic of how it has lead me to realize I was wrong about something, it's helped by tons of times. Sometimes I'll find myself in an argument resisting what the other person has to say and then I notice how silly that is and I consider whether I need to update. I've changed my mind about a number of mostly trivial things in this manner. Rationality (and less wrong in particular) helped me understand that winning an argument by stubbornly remaining wrong isn't really winning, and that has benefited me greatly. It can also help us be more strategic, and I think I've become a bit better at planning. I know some of this might not answer your question exactly, but it's a mainly response to your title.
If you are already an atheist that does not believe in ghosts, what can you learn from rationality? I'd love to be wrong about lots of things but my problem is, I think I'm right.
As far as I can tell, none of this reflective thinking has lead to deeper understanding of consciousness. (A subject I wish I wasn't so interested in, because its study seems so futile).
If you feel like it, please tell me about any particular instances where actively working on your own thought processes has lead you to realize you were wrong about something (other than blatantly false things like those I mentioned above) or if the same program lead to any new understanding of consciousness.