I guess the real test would be to take a young horse and never shoe them. They go the first couple years of their lives with just trimming, and somewhere around two we change that on them when they start work. What if you could start one barefoot instead of trying to convert one.
Or take something like my pony, who has been barefoot likely her whole life, but would she actually hold up under work or rougher ground? Her feet start to chip and break unevenly at about 9-10 weeks. Even without shoes, she has to be kept even and filed. And I think it is vital to their long term soundness that their feet are the same on both sides, that one isn't more worn or more chipped than the other at any given time.
Celia has a horse that she started working him barefoot, and rode him barefoot for several years, even up here. He could trot over gravel and it never seemed to bother him. Then she took him to a competition ride in Ark. She said she had never seen rocks like they had there. It was the ride from hell she said. Well the horse got really really sore, and she had already entered another ride for 2 weeks later. She had no choice but to shoe him. She left the shoes on him for 6 weeks then pulled them. He's never been able to go over the rocks barefoot as well since then. She regrets ever shoeing him.
That is why she's going to try barefoot again too. She thinks it can be done. It will just take awhile for the horse to get back to that "natural" foot that they had before shoes were ever put on. The difference between her and I tho, is she does not ride as much as I do. If her horses get rode 2X in one week that is alot for her. So it is hard to say the same would work for me.
Becky