[BrianG]

From lots of research and experimenting with switching BEC circuits, I've found that heavy loads (and/or shorted) on the output is VERY hard on the Schottky diode, and can also saturate the BEC coil. Not to mention if the main switching FET goes bad. Do that enough and I can definitely see it weakening or even failing.

A cap definitely helps supply a little extra current boost when needed, which makes the BEC "see" a more steady current flow. I would say anything around 1000-2200uF would be ideal. However, too much capacitance can cause issues on initial hookup when the caps charges. Of course, a cap won't help a BEC that has already been weakened, so don't wait to install one if you are using the MMPro in a heavier vehicle and/or powerful servo.

Obviously, a low ESR cap would be better, but regular 85*C caps are still better than nothing. It's really a simple matter to either buy a pre-made cap/connector or solder a servo connector to a cap, so there's no excuse not to run one.