I am not going to read through all of this, but I have done a fair bit of study on it. Here are some observations.

Hi-Viz is best in low light conditions, but loses some of its effectiveness (contrast) at noon. Dawn/dusk/fog/rain/overcast is where is works best.

In darkness Hi-Viz is no better than white, but not worse either. Retro Reflective is best at night.

The aforementioned post on the effective silhouette is huge and what we should be focusing on. Cras, trucks, busses typically have solid color bodywork that covers the whole vehicle. This solid, large color stands out on a cluttered background. Some colors work better than others, but the key is a large chunk of one color standing out against others.

Motorcycles are visually chopped apart, with the exception of the Honda Pacific Coast, most of them have some contrasting colors going on. We are already a smaller vehicle, now visually shop us into little pieces of different colors and racing stripes and see-through mag wheels and you get the picture.

A solid white snowmobile would be hard to see going up a snowy hill, add some black stripes and it would be easier, paint it solid black and it would be even easier, even though that color is not considered very good for conspicuity.

Want to see something interesting watch a video of a group of zebras in a panic. It is very hard to judge an individuals speed and distance its a visual mess for the predator or (driver)

Soon enough all new vehicles will be required to have obstacle sensing radar, until then do what you can to stand out from the background you are riding through. WW1 ships used some pretty radical camo called razzle dazzle to confuse optical rangefinders. Is your gear and motorcycle creating the razzle dazzle effect?

I often hear riders claim their striped jackets and racer replica helmets make them easier to see, when the actually break up their small profile into lots of visually tiny pieces. It is actually very interesting to see how our brain stitches together info from our eyes. Its is not as smooth as we think, researchers believe their is some truth to "I didn't see them"

What can you do?

For starters a solid light colored ball, floating 6 feet above the road is pretty visible. Pick a solid white or yellow helmet. Perhaps a solid light colored jacket would also help. Also a solid color bike in a light color with full bodywork will also help a little.

I have been in arguments with people over DLRs on cars. They say they do not make motorcycle less visible, they just make cars more visible. In reality it is all about the contrast, in the old days if you saw anything with its headlight on in the daytime it was almost always a motorcycle. To visually stand out now I think weird color lights, yellow, amber or one of each in s strange pattern not normally seen helps. Maybe stack two amber lights down low on your right side?

I hear people say ride like you are invisible, but in reality the best practice is ride like they are out to get you.