This is just one study & not sure if this link was in a thread or not–time crunched here so apologies if it is a repeat. Hopefully Dan allows this as it is an informative article on barefoot running vs. with shoes & not intended to promote any kind of other media or anything… http://www.dailycamera.com/...nning-less-efficient
Hopefully you all will find this interesting (or not).
*Edited to change “Studay to Study” 
I’m not a barefoot runner, but that was a bad study for a number of reasons. First, it should really be titled "running in lightweight shoes is more efficient than running in socks and running with thin strips of lead attached to the top of your feet. The subjects never ran barefoot.
Second, BF running was more metabolically costly than running in shoes. Isn’t that the point? It stresses your system more, thus likely does a better job of improving your strength.
And efficiency is very rarely the reason people run barefoot.
The big issue, is that I know many of the subjects were experienced barefoot runners, but as long as they were habitual shod runners, they are almost always likely to be more efficient in shoes. You become best at what you do habitually. Thus if they ran more in shoes (which I believe all subjects did) than of course they were more efficient in shoes!
Here is the abstract which may be more informative than the linked article. FWIW, Rodger Kram is one of the most respected experts on running biomechanics in the world. Of course that carries little or no weight here on ST.
Med Sci Sports Exerc. 2012 Mar 2.
Metabolic Cost of Running Barefoot versus Shod: Is Lighter Better?
Franz JR, Wierzbinski CM, Kram R. Locomotion Lab, Department of Integrative Physiology, University of Colorado.
PURPOSE:Based on mass alone, one might intuit that running barefoot would exact a lower metabolic cost than running in shoes. Numerous studies have shown that adding mass to shoes increases submaximal oxygen uptake (VO2) by about 1% per 100 grams per shoe. However, only two of the seven studies on the topic have found a statistically significant difference in (VO2) between barefoot and shod running. The lack of difference found in these studies suggests that factors other than shoe mass (e.g. barefoot running experience, foot-strike pattern, shoe construction) may play important roles in determining the metabolic cost of barefoot vs. shod running. Our goal was to quantify the metabolic effects of adding mass to the feet and compare oxygen uptake and metabolic power during barefoot vs. shod running while controlling for barefoot running experience, foot-strike pattern and footwear.
METHODS: 12 males with substantial barefoot running experience ran at 3.35 m/s with a mid-foot strike pattern on a motorized treadmill, both barefoot and in lightweight cushioned shoes (150 g/shoe). In additional trials, we attached small lead strips to each foot/shoe (150, 300, 450 g). For each condition, we measured subjects’ rates of oxygen consumption and carbon dioxide production and calculated metabolic power.
RESULTS: VO2 increased by approximately 1% for each 100 g added per foot, whether barefoot or shod (p<0.001). However, barefoot and shod running did not significantly differ in VO2 or metabolic power. A consequence of these two findings was that for footwear conditions of equal mass, shod running had 3-4% lower VO2 and metabolic power demand than barefoot running (p<0.05).
CONCLUSIONS: Running barefoot offers no metabolic advantage over running in lightweight, cushioned shoes.