I have my ESC near the servo and the battery in the rear close to the motor. I haven't been able to do a proper shake down on the car yet so I can't say anything about it's performance. I checked the center of gravity of my car and it's near the middle, just slightly forward. I plan to get some run time this week and then next month try mounting my ESC in the rear and see if there is any difference.
But if you want the "cleanest" layout, the ESC should be in the rear near the motor. That would eliminate lots of wires running almost the 16cm to the motor. But note you would need a short (55-75mm) brushless sensor cable.