Dealspeed - the expanation was not quite right
torque is torque is torque ----digital or analog circuitry.
The difference is HOLDING TORQUE or "holding power" in the advertisments.
All servos follow the input from the TX control stick-
The servo moves to align with the stick position.
Pretty straightforward--
Here is the difference:
As the servo approaches perfect alignment with control input (stick control)--the power to the servo motor lessens -until it is simply sucking enough to center.
As you move the stick OR if the control surface tries to move --more power is fed to the servo motor as needed to HOLD the intended position.
Analog feeds this power in a smooth , rapid curve .
BUT
Digital will provide full power to the servo motor, quicker- which means it will HOLD the intended position much better
This is a very important feature because most precision flying is done using teensy weensy stick movements.
In actual practice -this feature can be felt, simply trying to move the control surface a little bit
It feels "locked in" on the digital and a bit softer on the analog
That's it . All the hubub about differences is just in how well the servo HOLDS position .
And that -is very important for preventing flutter and providing accurate control
It means nada as for total ability to move the surface ( that is torque rating)
Servo speed rating -yet another rating - is another misleading term.
If the load on the surface is low --really low - it can move faster but typically these servos trade speed for power and that is simply not a good trade off.
Best servo?
ANY digital-- properly sized and using good linkage and using maximum rotation to surface throw ratios.