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IME it makes no difference
This is about right. A decent set of lights makes anyone more than visible enough for night riding under city lights. The biggest reason for drivers not seeing is not looking.
middleofnowhere-
No city lights here! It’s tractor lights at best!
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Side-on those ProViz jackets stand out a hell of a lot more than normal cycling stuff (i.e. normal cycling jackets with reflective piping). Haven't tried one to see if they're boil-in-the-bag or not though.
The worry will be that soon loads of people have them, and then that's all drivers will be looking for. It's a different take on the lumen escalation war.
The biggest reason for drivers not seeing is not looking.
Personally I'd say the biggest reason for drivers not seeing is not looking properly. A big reflective jacket like that is going to increase the chance that you'll be seen by someone who's not looking properly (i.e. just giving a quick glance). But, yes, for the people that pull out (or across you, or into you) without looking *at all* there's no magic jacket that's going to help.
(For side-on visibility I currently have spoke reflectors on both wheels and I've had loads of comments from people about just how bright they are in headlights.)
Rhobbs
Greenbank
IME it makes no difference, but if it makes you feel safer ... go for it.