Malzahn's play calling board

I just bought and read Gus Malzahn's The Hurry Up, No-Huddle book, and I was wondering what you guys thought about his play calling board- incorporating colors and numbers to tell who was the hot signaler and what pass play to call.

In theory it seems like a great idea, but I was wondering if anyone had used it. How do you keep people from stealing your signals? Is it easier to use than just signaling in plays with your hands?

I'm looking forward to the board's thoughts!