Occasional or regular non-bike helmet cyclist?

[oz rider]

And I sure would like to see good data on injuries and risk beyond anecdotes.

Thank goodness. There are resources here. And yes, we killed more on the roads (no cyclists afaik) this Easter than have died in Afghanistan, but the Prime Minister won't be attending the road victims' funerals. People are not very good at assessing risk (not even distinguishing between utility and sport cycling), which is one of the reasons the anti-compulsion groups dislike MHLs; they make cycling look dangerous.