I don't endurance ride, but I do ride 5+ hour trail rides in the mountains.
I use Easyboot Epics. I use them because I think my horses feet are healthier barefoot. No contraction, overgrown hooves or crappy farriers to worry about. (Not saying all farriers are crappy of course, I learned from farriers and used to shoe my horses myself). But some of the farriers I've used
have done a crappy job. And I have enough knowledge to realize when they have done a crappy job!
I have never lost a boot in the mud and I feel they give BETTER traction over solid rocks and pavement. (Loose gravel not so much though.) And you are actually less likely to get stone bruises because the entire sole is covered. I've never had heel rubs in the Epics either.
To me it comes down to the effort the owner wants to put in. You have to decide if the benefit of boots outweigh the labor involved in fooling around with taking them on and off. I have a friend whose horses are shod. She just gets on and rides and never worries about feet. Unless she looses a shoe. They she is stuck waiting for the farrier. I never have to worry about that.
On the other hand, I have to decide at the beginning of a ride whether I want to boot my horse or not based on the terrain. Some rides we go completely barefoot. Some rides I boot before the ride if I know the terrain is rocky. Some rides I carry the boots with me and put them on if I think we are encountering too many rocks. It can be a pain in the butt sometimes I must admit! But I normally only have to boot the fronts. And some rides we don't have to boot at all. And my friends are patient if I need to take a break to put on the boots.
It works out well for me because I do my own trimming and just totally take care of their feet myself. I look at boots like my own tennis shoes. When I am at home (or the horse is at home) we can go barefoot. If the terrain is fair, the horse can go barefoot. But my horse will be riding in rocks for a prolonged period I put his tennis shoes on.
Many endurance riders DO use boots. Mostly glue-ons (like the Easyboot shells without the "gaiters." ) Go to Easycare's website and you can learn more about that.
Mainly it is labor intensive. Shoes are easy. The farrier does all the work. But some people feel the benefits of boots outweigh the hassle. To me the main benefit is keeping my horses barefoot 99% of the time to keep their hooves well maintained and healthy.....which fortunately I am able to do myself. But I admit shoes are easier and if I had to boot all four feet everytime I rode I would probably go back to shoes. If I had to hire a farrier for trims I would probably go back to shoes. But I DO know my horses have wider, less contracted feet barefoot.
I don't think there is anything inherently wrong with shoes. But I do think there are a lot of owners that don't know their farrier is less-than-great. But if you don't want to hassle with boots (and it does take a patient person)
then shoes would be the way to go.