That last thing did eventually happen - she snagged a shoe when we were in the woods. It was so twisted she couldn't walk on it, so I had to pull the shoe and walk at her side 5 miles home. I was surprised to see that her unshod hoof was no worse for the wear after that, so instead of replacing the missing shoe I had the farrier pull the other 3. We never went back to shoes after that, even in winter - just had the farrier trim on schedule. She never had a problem all the rest of her life. No thrush, no splits, no leg problems.
A similar story is what led me to learning more about hoof health and barefoot only hoof care and eventually led me to becoming a professional barefoot trimmer. Weirdly enough that path eventually led me to aikido...
So I mentioned these shoes to my chiropractor today who was very enthusiastically positive about them. He said they really are good for back problems. It seems that the tendons etc in our toes lead to our backs and that as our toes flex and bend on natural (not flat) surfaces those tendons etc inform our back muscles how to stabilize our bodies properly leading to less strain. So these shoes that allow our toes to flex and bend individually in a more natural way have a lot of benefit for our whole body health.
I think I'll be giving them a try in the near future.