I have built several quadcopters, hexacopters, and octacopters. This means that between the flight controller (I use 3DR APM2.6 or Pixhawk) and the motors there are heavy duty power wires as well as a servo-style cable carrying a PWM control signal for the ESC. Three short heavy-duty wires then connect the motor to the ESC, one for each phase.
Several times I've heard or read people saying that the electronic speed controllers (ESCs) should be mounted far away from the flight controller (FMU seems to be the abbreviation en vogue) and close to the motors. I think the idea is that this cuts down on interference (I'm not sure what sort) that could be emitted by the long ESC -> motor wires that would be required if you have the ESCs all at the center of the aircraft. Another consideration is that ESCs can be cooled by propellers if they are right under the rotor wash, as mine usually are.
So, I've always mounted ESCs close to motors, but realized that design could be much simpler if ESCs are mounted centrally. So, my question is: what are the pros and cons of mounting ESCs close to the motor versus close to the FMU?