Madrigger the DS821 is more than enough servo to do all the surfaces on a .60 sized stick.

like CGretired and Bruce said, make sure that both aileron servos are the same brand and model
and you don't need an 821 on the throttle. alot of experienced and competition pilots use a smaller
servo like the hitec HS81 on the throttle as it doesn't need alot of torque to operate.