I have been following the barefoot posts with interest. Someday, maybe I will get the courage to try it, but I want to share a few observations. Please feel free to point out if I'm not getting this :)
I understand that the hoof grows more with more use. I just want to say that one of my horses, even when shod, grows much faster with more use. When we are training/conditioning, 4 times a week, I need to have the farrier out at least every 5 weeks, sometimes 4. The hoof grows faster, and of course the shoes wear. So I don't think having shoes on them restricts blood flow to the point that is being discussed here. Maybe I just have a good farrier, or a horse with great feet.
I have to admit, I haven't tried the barefoot trim, but then I don't know of a farrier near me who is educated enough to try it, and won't experiment with my horses. Also, to get the feet to a point where you can go without shoes, you must really slow down the conditioning at first, which can really mess with the ride season (we have a season year round because of the weather). So unless you have a stable full of horses that you can switch off, experiment on, I don't see it as an alternative. Wish I did, would love to have a stable full of horses :)