I have made this recipe multiple times now and every single time it has resulted in the easiest, juiciest turkey you can imagine. You don't even have to do it on bread, you can use a roasting rack or oven-save trivet.
Basically what happens here is that the breast meat is insulated by being within the baking tray. At the same time, the fluid from the back (juices and fat) flows down towards the breast. This results in not only juicy turkey breast meat, but self-basted turkey breast meat, meaning you have turkey flavor instead of bland breast meat. Also, the dark meat is exposed to the air, allowing it to fully cook at the same time. Essentially, you're mimicking what happens to a rotisserie chicken.
The only down-side is that you do not get really good breast skin. BUT you get a fuck ton of skin from the back and sides that you can easily remove and serve instead!