If you watch a Paso Fino they have a similar movement to a burro. The legs go up and down underneath themselves, instead of extended out behind and in front. If you watch where a saddle goes on any other breed, it is placed higher on the withers so that the horse can support the weight placed on them. That is because, traditionally, a horse carries 60 percent of its body weight in the front end and 40 percent of its body weight in the rear end, with a sleight back and rib carriage suspended between. That is why your longer backed, taller horses can not carry as much weight in the center of their back, unlike a burro or a Paso Fino.
Small size enhances their ability to carry a bigger person.
It has to do with conformation, or the way a horse is put together. The longer the back, the longer the leg, the greater the extension in stride, the less weight a horse can carry in the center of his back and the rougher the ride. They will leave you and your big horses in the dust on the trails. The Paso Fino is like a finely tuned sports car. They have a powerhouse, energy efficient engine, with all the comfort of the smoothest ride in the horse world.