Mark, it comes down to the construction style of the motor. A coreless motor is the highest evolution of brushed motors. As a motor itself, they have good spin up qualities, and are fairly inexpensive to produce. Brushless are essentially like we use in our cars. They will be more efficient in operation and when used correctly with software (a servo is really a motor, speed control and some gears), able to more precise in operation.

Biggest issue with brushless servos in the past have been price. And we have worked hard with Xpert to bring the price down to almost that of a coreless unit, but with all the advantages of efficiency and control you get from brushless. We don't see the big spikes that can effect BEC, and brown out a receiver. They are very efficient so not taking any extra voltage from the battery.