As Yvain's post said, it seems hard to find people who benefited a lot from LW-rationality.

I think LW has at least made me better at handling disagreements with others. For example I'm rather embarrassed when I look back on my early discussions with Nick Szabo on cryptocurrency and other topics, and I think a disagreement I had a few years ago with my business partner was also helped greatly by both of us having followed LW (or maybe it was still OB at that point).