Looking at the picture I found of the E-Z trail, I have two farmhand forage boxes that have an auger in the bottom that goes back and forth, just like the E-Z trail.  Unloads nice and evenly, I have broken a few shear bolts that drive the auger when unloading ryelage, but it works great on corn.  Not the greatest in grasses though, since they tend to pack in the box and not break apart as easily as corn when unloading.  Probably wouldn't work at all for shelled corn, since it would flow around the auger and lock it in so it couldn't start.  Always make sure the auger is under the shelf before loading.  If feeding off of one, be very careful about starting it the next feeding when the auger sat stopped under the load and not the shelf.  When unloading forage grasses (hay, rye, sudan grass, etc.)  don't run the tractor too fast (half throttle is usually OK).  It looks like they possibly bought the wagons from Farm Hand, and changed a few minor details and re-branded them.  On the Farmhand there is a cam (offset lobe) to operate a cam follower that moves a one-way bearing to drive a shaft that moves the auger across the wagon.  When in grasses, and you run the tractor too fast, the lobe will slap the cam follower, since the auger actually moves under spring tension, and it will break the cam follower.  They have their good and bad points, but if cared for and understood on the limitations, they work good.