I'm on the flip side of this thread, where neither horse is shod and do very well on all types of terrain.
However, T , my 21 yr old mare, does not grow hoof like she use to. After a couple of long rides on gravel (4 -5 hrs each time), her hooves are worn right down.
So, if I decide to continue taking her on these longer rides on that type of footing, I'll probably have to start shoeing her again. Must be an age thing, as this was never an issue before last year.
Be the kind of woman that when your feet hit the floor each morning the devil says, "Oh crap, she's up!".