My girl can't go barefoot. I've had the vet out to check her. He said that the sole of her hooves are lower to the ground than normal and her coffin bone is also lower to the ground (though she's never foundered or anything) and it causes her pain to walk on hard ground very long. I kept her barefoot for a year once, and she was so tender that whole year that I could barely ride.
My farrier agrees with the vet that she needs at least front shoes. I am calling the farrier later today, as he wasn't home yesterday.