This is great! – Are you planning to test mobile navs as well?
The research is from 2004. So a bit outdated I think. I wonder if it applies to modern everyday webshops, who almost all use a different navigation.
So interesting, thanks for sharing! I recently wrote a post about dropdown menu design: https://www.newmediacampaigns.com/blog/ten-examples-of-dropdown-menus-on-websites
Some of the examples follow the formats you discussed!