No disadvantage unless you count that your wallet is about $160 lighter.
Weight savings. Far less drivetrain vibration (resonation) after a gear swap. The aluminum d/s can flex 17 degrees compared with the steel one that can flex about 3 degrees. This helps reduce the shock to the rear/axles during a hard launch. I've also seen claims of about 2-3rwhp increase due to some of what is mentioned above but I cannot verify that.