Will labels help protect CD's?

My brother has a DJ business, and made copies of some of his CD's for certain compilations. He bought a labelmaking kit and some CD's at the store, and after burning a CD, he does something on the computer that prints the label, which covers just about the whole surface of the CD. The kit includes some round spring loaded thing where you put the label on it upside down, then put the CD on top of it upside down, press, and the label sticks to the CD and is perfectly centered.

I was wondering if I should use something like this to help ensure protection for my CD's, even though the bottom surface is still exposed.

Is the reflective layer on the top or the bottom of the CD, or somewhere in the middle?