UVLayout is simply the most cutting-edge unwraping tool. Just think of some functionality - and voila - it is already implemented in uvlayout. Simply fantastic and outstanding tool. BUT! You'll have to invest some time to learn all the operations and hotkeys, because it's interface is a real HARDCORE.
If you posess a licensed UVLayout USB-dongle - nobody will ban you from using it! :) The "out of the box" UV tools of Maya or Max are incomparably petty. Using third-party script or plugins really makes working better - but not THAT RADICALLY as UVLayout does. IMHO.