I've carried a lot of stone and gravel and find it essential. Maybe 10 dually loads, up to 3,000 lbs but usually right around the 2,000 it's rated for.
I've "brackets" for my Reese 5th wheel/goose neck hitch so I lay in a few 2x4's then put down a sheet of plywood to "level" my bed, then a tarp (HF), then the mat, then the unloader, then have them drop a ton or so on top. The tarp is big enough to go up the sides and I can pull it over so stones and dust do not fly out. And if the "or so" becomes a lot I generally get my son to shovel some off the top first. I don't want to rip the unloader.
After the load is "cranked out" it's fairly simple to "disassemble" and pull the tarp and what is left out.
I've also used it when Lowes mis-priced some 12x12 concrete flagstones and I picked up two bed loads. I used it to crank the pallets they had pushed to the front of the bed back to the tailgate.