Had reason to consider this again on a ride yesterday.
Much like good old helmets, I'm simply pro-choice on this. If you want to wear bright yellow then fine; if you don't want to wear bright yellow then fine.
What I find odd is that people will say, in an absolute fashion, that one or the other is more visible. The thing is, life is never that absolute.
I have photos in bright sunshine of dark clothing standing out waaaaaaaay more than alleged hi-viz. But yesterday on a run in the Borders with my other half and her dad, after stopping for lunch he produced an as-yellow-as-yellow-can-be jacket. And by eck in that dull gloomy light of two in the afternoon out in the middle of nowhere he stuck out like the sorest of thumbs.
It's all in the context. Basically anyone who takes an entrenched view one way or the other is closing their eyes to the reality of different conditions. That is all.
p.s. one thing I would say, in the dark, forget the debate between hi-viz or not, what you really want is reflective.
p.p.s. for the record both Mel and her dad wore a helmet, I didn't, no antagonism, no disagreements. Live. Let live. Mel used to not wear one after reading the same stuff as me, took a long break from cycling, and having got back into it has decided she wants to wear a helmet again - I'm just happy she's back on a bike.