What's wrong with Brushed motors:
Periodic maintenance is required, and many customers do not have a lathe to turn the commutator. They have a Lower speed range due to mechanical limitations on the brushes. The brush arcing generates wear and electrical noise. If it's in a lock can, it's disposable. If you run it hard, it will have a short life. They are heavy and inefficient, when you compare them to the AC brushless motors most of us use.
Brushed DC motors, Brushless DC motors, and Brushless AC motors all use different controllers:
Brushless DC motors, and Brushless AC motors are both controlled by a DC electric source (let’s say an 11 volt battery) via an integrated inverter which produces a 3 phase AC electric signal to drive the motor. The biggest difference between the Brushless AC motor controller and the Brushless DC controller is the AC motor controller uses sin waves that vary from -11 volts to +11 volts, and the DC controller uses Square waves (pulse) that vary from 0 volts to +11 volts.
The biggest difference between the Brushless motor controller and the Brushed controller is, the Brushless motor controller controls speed by varying the frequency of the 3 phase AC electric signal that it generates, the Brushed controller controls speed by varying the voltage of the DC electric signal that it sends to the motor. If you control the motor to run at a lower RPM the AC ESC saves energy, the DC ESC waste the energy by turning it in to heat.
Brushed motors and NiMH batteries are so heavy and out dated. A brushless motor and a LiPo battery are Cheaper, more reliable, and have significantly more power at less weight. The ESC is also a lot cheaper and more efficient.
Post number one in the
thread has many short cuts that may interest you, like this one
How an AC Motor and its ESC work !!