Michael,
I've found that deer antler, which I assume is the same as buckhorn, hits a little softer than ivory.  Since the outside diameters machine similarly, I think the difference in hit is due to two things: first, my deer antler ferrules are sleeve type ferrules vs. the typical capped ivory style.  Second, deer antler has a porous core which may not be completely removed in the boring operation.  This density difference may contribute to the softening of the hit.  That said, I love the way they look, hit & feel.  Durability doesn't seem to be an issue, either.  I have some out there that are 12 yrs old & still playing fine.  The only reservations I've heard concern the appearance.  Most of the antler ferrules are far from being the pristine white of ivory.  They tend to have a grayer & mottled finish.  I don't think the local deer are watching their diets properly.  Personally, I find it unique & quite attractive.  There is a depth to the polished antler that isn't available in synthetics.