Hi,
There are several features that are different. One is the end-point hold you mention. Another is the calibration. This function calibrates neutral to match your transmitter. What this means is that when you reverse a servo its centering does not change. It also provides a more accurate calibration of the linear function that defines the modification of the end-points. Another feature is the servo priority mode where the servos that have not been calibrated are turned off. This means that if you have 3 servos connected to the 3D and you start with servo A the other two servos are turned off which keeps them from fighting servo A. With the Matchbox you have to unplug servos B and C while working on A. When you move to servo B, servo A will be running but servo C will be turned off. Of lesser note, the auxiliary power is controlled by an electronic switch instead of the plug that is in the Matchbox and there is a failsafe mode for FM transmitters. I hope this helped. If you have more questions please feel free to ask.