I am a firm believer in accident data and statistics. My primary faith in them is that politics and greed do not appear to have tainted the data. As such, most (~80%) motorcycles accidents happen with the motorcycle hitting something in front of them. If a headlight(s) aren't making you more visible - a hi-viz jacket or helmet will not either. Hi-viz will not help with cell phone users, distracted drivers, bicyclists, slower traffic, etc.
I believe (with no statistical or anecdotal evidence) that one is less likely to get run over by following traffic after falling off a motorcycle on a busy highway when wearing Hi-viz. I also believe that the chances of getting hit from the rear are slightly reduced when wearing Hi-viz. But, the improvement is slight. Where I see Hi-viz being a more significant improvement is when riding with traffic in multiple lanes in the same direction. While the accident rate is already low in such circumstances, I still believe Hi-viz provides some benefit.
The above is not to discount the psychological effect of color schemes on human behavior. When people are conditioned to slow down around construction crews and others in the road wearing Hi-viz clothing that same effect should be associated with a motorcyclist wearing Hi-viz. However, that is conjecture on my part.
I always ride like I am invisible. With such a mindset, having a black jacket may provide some psychological advantage - as in "damn, no one will notice me while wearing this". I also ride with the mindset that all drivers on the road are morons and retards with barely enough ability to operate their motor vehicle - as in "I need to keep an eye on this moron".