At the very least, it can't hurt...
Like a few have mentioned, I noticed a difference in driver behavior when I started wearing hi-viz. Car drivers left a little more room, cutting in front was less frequent and there were fewer events of pulling out of side streets or left hand turns that caused hard braking.
My theory is that in addition to being more visible, car drivers perceive hi-viz riders a little differently; there is probably a strong correlation between wearing hi-viz and other passive and active safety behaviors (wearing ATGATT, being aware of good positioning in traffic, etc.) and many of the negative stereotypes drivers associate with riders don't translate to hi-viz riders as strongly. I think I get a little more consideration.
It's only one part of my plan to mitigate the risks but it's pretty high on that list.