It's an old idea in South Texas. They work well.
I actually got one from my dad (CanyonAg77) for christmas this year made from a a disc used on our farm. Here's mine:







I've used it to make breakfast, dinner, etc. This one was a bit of a prototype and he's been working on stands/larger discs and other stuff since I got this one.
I'm a huge fan of cooking with them. They're thick and heavy, and angled kind of like a wok. With a smaller burner, the middle can get very hot and the sides can stay warm, so I can make bacon first, cook the toast in the bacon grease thats collected in the middle of the disc with the bacon pushed off to the side where it won't burn, push the toast to the side and cook my eggs too, then throw it all on a plate.
No experience with their version, but one made from a good plow disc is a heck of a lot of fun to cook with.