If you have a place to run barefoot without stepping in dog crap. glass, needles and bottle caps, then go for it. For the rest of us, the Free is a good alternative - that and they are really comfy to wear around the house.
Has anyone seen the racing flat that Nike makes that is similar to the Free - no upper to speak of, just some flimsy material. They have a warning on the inside saying that you shouldn’t use them for more than 100K. Wicked light, though.