Studys on different types of hoods?

Does anyone have any links to studies on different types of hoods. specifically which brand/models perform better over others? I want to upgrade my cool tube to something else. I am leaning towards an adjust-a-wing because it seems to have the best spread, and has no glass to impede the light.

Has anyone came across any scientific studies in different brands and/or design types? I would like to take personal experience to a minimum and focus on hard facts. But if you have any personal experience feel free to post as well.