I think try it, and if you see any signs of tenderness or lameness, or the hooves chipping away, then go to shoes. Do you know a bit about the history of your horses hooves?? If it has been barefoot from birth the hooves will have been allowed to strengthen and develope correctly, and shouldnt have any problem at all continuing barefoot.
You will know well before your first endurance ride if your horses hooves are up to it or not, so don't let that worry you just yet.
What do you mean by goo?? A moisturizing agent?
I love bare feet. All my babies are unshod and they have excelent hooves. They are so tough, and they grow out so evenly now, and are very balanced and no flares. At first I was really worried, because we have only one farrier in the area and he is less than not good, so I taught myself. For a long time I was affraid I was doing more harm than good, but there hooves are so awesome now!!
Even my thoroughbred, who had horribly overgrown and weak hooves when I got him 4 months ago, has been barefoot for the last month and a half, and just in that little time they have improved so much.
You have the benefit when barefoot, of being able to rasp regularly and as needed. Unlike with a shod horse, whos hoof is allowed to grow and grow and grow for 8 weeks (sometimes longer!!) and then suddenly and harshly cut back to next to nothing. I have wondered if this has an effect on the alignment of the leg bones and pedal bone, in the very long term.
You also have better grip (on all terrains, shoes can slip on asphalt - keep that in mind if you plan to cart through town), better shock absorbsion, easier to care for, less expensive, and it is something you can learn yourself, and requires much less physical exhertion that shoing. Im sure if you talked to this farrier he would be more than happy to expain the anatomy of the hoof and how it works, the effects it has on the leg, and the benefits, as well as give you a basic rundown on how to do it.
Another great thing about being barefoot is that you never have to worry about throwing a shoe, especially when you are way out in the middle of nowhere. There would be nothing worse than having to ride miles home on a horse unballance with 3 shoes, and a hoof that isnt conditioned for the terrain.