We are curious about the claim that it is faster. Understandably, you would think going from 2005 to 2012 versions should be, but the few clients who have chosen to try an upgrade have found it slower on the same hardware.
6.3.3 currently remains the gold standard for stability and reliability.
We have been asked often about the steady drum-beat to upgrade recently, and while I could opine, the reality on the ground is a mixed bag at best.