It's the cheap kind ($5 or $10) you can get at sport outlet stores or even large super markets. They have a TPR (rubber) outsole and an EVA (foam) insole (which I removed). The upper part made from nylon mesh and some thin neoprene.
But going barefoot allows my feet and toes to flex freely and feel the surface. I am able to use parts of my feet and legs that used to be constrained by my running shoes (most notably my arches and calves). Because of this, my running gait has changed a lot. After years of pounding the pavement (striking heel-first) I am able to run smooth and easy, and it feels great.
Thanks to this new running style, there is hardly any wear to the soles. I think they will last around 500 miles. After that, I'll just spend $10 on a new pair.
(You are talking about the kind for divers? I also have them for kayaking. And I've always been very careful with walking on stones, etc.)
Do you mean the kind of new "shoes" they discuss in the article?
I feel like listening to a chef discussing wine and then ask about the color of his shirt. :-)