Aluminum Cases or Back Replica?

Hi, I bought this JustCase Metallica case, http://www.amazon.com/JustCase-Metallica-Verizon-Brushed-Aluminum/dp/B005LT6T3M, which is pretty cool, but I wonder if I can be more metallic. :-)

The case is made of some synthetic material, and there is only a layer of aluminum on the back. I also saw that Amazon is selling iPhone back glass replica made completely in aluminum, which is also pretty cool, (especially if you broke your back glass and don't want to pay the $99 to get it changed in Apple store), and I would like to ask people who has used those back replica if it degrades the phone signals.