Excellent question. I've only seen Brad Gillis, Jake E Lee, Joe Holmes and Zakk Wylde play Randy's material. Each has their own unique approach to playing live. Brad loved the tremelo bar and always liked to put it into many of Randy's songs. Jake plays with a lot of fire and adds his own fills. His sound is also quite different than Randy's. Zakk loves to play some version of the Tribute album and is the master of the pinch harmonic. Joe seemed to keep the closest to the record- at least from the limited bootlegs I've seen and heard...
To be a teacher you must never stop learning yourself...