Is it jitter or are the servo's buzzing? All digital servo's make noice, they are constantly trying to perfectly center themselves.

That Gyro will work just fine with a JR setup, but I highly reccomend the 9254 or 53 servo with it to get max performace.

Heres a great guide on Futaba's site for setting up that gyro.

http://www.futaba-rc.com/team/team-tip-002.html