Is the SNS disc or HD based?

I am asking since I really would like a HD based system.  I just picked up my first Scion a few days ago (2008 BCM Xb).  I had a Magellan 760 installed sitting on the dash in my Silverado, mounting it in the Xb would put it out of arms reach (at least in the center).  By biggest complaint with the Xb is the single 12V outlet, my Silverado had (3), I was able to plug in my GPS, Sirius Sportster 5 and my cell phone without having to worry.  Disc based GPS systems seem to take longer to reroute than HD based systems.  I guess I am going to have to pick up the Toy-SC1 and transfer my Sirius subscription over the one of these units to be able to use the factory head deck.  if I were able to replace my Magellan with the SNS, then I would only need the one 12V for my cell phone. 

For those that do have the SNS, how quickly does it reroute.