We've had the natural feeder about 2 1/2 yrs now. The drafts eat till it's empty and then use it for a soccer ball. That feeder has taken some serious abuse. The only maintenance we have done is file some edges off the grate.
This one is cool, but there is no way it would work for my horse....
Slow Feeder Saver Hay feeder
My mare has a VERY heavy duty shipping crate....looks similar to the fruit bins the farmers use, but is much more heavy duty. It weighs at least 100lbs itself. She will take her hoof and make it look like Stonehenge like it is nothing. I now have it tied to a fence post which is a railroad tie cemented in the ground five feet with heavy duty strapping.