I'm also having an interesting shod vs. unshod dialog with my minimalist barefoot friends. I asked a few questions.
First, I mentioned that all the current World records and recent Olympic gold medal times have been set by runners wearing shoes, and this is a simple fact although many of my friends are unable to acknowledge that. I asked if top elite runners could run the same times barefoot as they do in shoes. Second, do shoes provide any advantages to those runners, whether physical or mental.
I'm a big proponent of at least some level of barefoot walking or running but many of the same holes we poke in the shoe arguments can equally be applied to barefoot arguments. There's so much we don't know and there's too many factors to account for in running . . . no single study will ever account for every potential factor in the runner's performance.
With that said, the facts we have show the current fastest times were produced by runners wearing shoes and not barefoot. Sure, runners wear shoes for endorsement money but does one really think that an elite runner would disregard barefoot running if they could run faster barefoot? A runner would not sacrifice the opportunity to break a world record just to wear shoes as there's more endorsement money for the runner that sets a world record and/or wins an Olympic gold medal.
Unfortunately, there's probably only a handful of runners that could give us valuable insight. Runners like Haile G. or Tirunesh Dibaba who grew up barefoot, switched to shoes and set world records . . . they could tell us whether they could run the same times barefoot and/or if shoes provide them with any advantages.
Harry
