8411 and 2721 gears/deadband
I've been trying to dig up the numbers on the dead band of the servos. Here is the info I have right now.
1. The gears are not the same, but they are similar materials. The 8411 has a wider bearing spacing on the output gear which makes it have less wobble.
2. The 8411 has less than 1 ms dead band.
3. I haven't found a number on this yet, but it is higher than the 8411.
4. Using the matchbox for adjusting the center and end points of each servo will allow you to make up the differences between the servos.
5. The center is determined by the pot, not by the gear train. Unless the pot is off, you can determine this by setting dual rates up at 100% on high, and 50% on low, and switching between them and seeing if the servo moves when flipping the dual rate switch, your servos do not need adjusted. If it does not, the pot in the servo is set correctly. If there are differences between the centering of the servos, you will need to use a matchbox to correct any difference, or have each servo plugged into different channels to allow you to use sub trims and travel adjust on each servo.