Here is a release from Futaba about their Brushless servos.

1. The brushless servos offer greatly improved response time over
other servos. Specifically, the response time on the brushless
servos has been decreased from 10ms to 7ms. This means that the
servos will react much, much faster to any control input.

2. Significantly increased life span. The new brushless servo
motors will last more than five times longer than servos that include
brushed motors.

3. Lower operating temperatures. As there are not any brushes on
the motor armature, there is no spark produced when the servo motor
is in operation. Thus, the temperature remains very constant within
the servo rather than increasing as they do in a brushed motor
servo.

Furthermore, thanks to the motor design, the outer coils act as a
heat sink dissipating any heat that does occur. As an added benefit,
Futaba is able to increase the torque or speed of the servos without
increasing the case dimensions.

4. Vibration & Shock. Unlike servos that used brushed motors, the
brushless servos from Futaba are less susceptible to the effects of
vibration and/or shock. While we don't want the modeler to abandon
the use of the servo grommets and rubber mounts, these servos are
simply less apt to experience difficulties from poor or improper
installation.

Additionally, the inertia of the standard motors also facilitates the
effects of vibration on the servo's performance. By eliminating this
inertia in a brushless servo, Futaba has reduced this possibility.

5. Power consumption. Brushless servos consume approximately the
same amount of power as their digital servo counterparts.

6. Centering. Centering is the same as it is with the digital
servos. The dead band is also equal to the digitals.

7. Case size. Brushless servos are the same as a standard-size
servo.

8. Increased resolution for smoother operation.

9. Samarium Cobalt magnet for better performance and increased
holding power.

10. Dual ball bearings.