Please forgive the thread necromancy, it's the latest date I can find on the topic.
Following my perusal of the h*lm*t debate (and conversion thereof!) I naturally enough sought this out as logically the next safety question. (Headphones/earphones due up next, though I rarely use them myself).
It seems to me that this debate follows a near identical path to the h*lm*t one by which I mean:
a) Everyone strives to be safer, an aim that is common from both sides
b) There appears to be a conflict between intuition/common sense and such statistical scientific data as exists
c) Emotions are apt to run high (though not as high as for h*lm*ts)
d) There is scope for victim blaming/transference of responsibility from motorist to cyclist
e) Some people somewhere have a vested (ha!) interest in flogging this stuff
e) Possible future compulsion (though less likely at this point than for h*lm*ts as far as i can tell)
I'm sure there is more, but on initial inspection that appears to cover the basics.
I confess, as I was with helmets (to heck with the asterisks), to originally basing my choices upon intuition and received wisdom i.e. the cops wear the stuff, the guys on bulding sites wear it and in some cases are compelled to do so, it looks bright, makes sense to wear it.
I further admit that thus far if my belief is that statistical data and evidence should overrule my basic intuition (it should, but like most I suspect, I still sometime struggle with this) the preponderance after 12 pages (phew, not 250...) is almost exactly the same as for helmets, there is no statiscal data supporting hi vis and much that says it makes no difference. I was wrong, for the right reasons, but wrong nonetheless.
Tangentially, but certainly interesting if one has not seen it is this:
Which is fun to watch regardless of your stance on hi-vis I'd imagine

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