2007 model year was no servo,the First GSA's in 2006 were servo ,I tried one,by the time my order was delivered(6 months) the servo brakes were gone.September 2006 that was.
Get the NO-servo model. I exchanged my 2006 GSA to a 2007 when I could get it without servo.
Tha servo gives you no adventage. Just noice, insensitive front-breaking at slow speed and battery drain!