all i can offer is every time i hear a packstring coming in the mountains i see its being lead by a horse that is kicking a rock know and again, when i am suprised there is a packstring in my camp its a guy riding a mule towing a couple mules, i have had many of each in all kind of conditions, horses raised in the rough stuff from day one, as well as mules raised in a backyard, i cant hear the feet on my mules hitting rocks, logs , whatnot, they use there nosess like a bird dog and ears like a mulie buck, i ask them to do things , not tel them to do it, kind of like a wife.....