The Starviper is a mobile ship in the same regard that the E-wing is because of its ability to take Advanced Sensors, but is not as naturally mobile as a PTL A-wing or Interceptor, and DEFINITELY not as a Phantom. The Starviper will have the same problems as the E-wing; more mobile than most, but not quite a flanker. Tougher than said flankers, but not a tank.
Access to native advanced sensors boost (a first, coming along with the Aggressor as well) and Segnor's probably gives it that sort of impression
Not that it is or isn't hypermobile. It can do either on a dime (slow roll with ALL the speed 1 maneuvers, native boost and b-roll) and balancing out the how and the when of these two strengths will be key to using it effectively

