Don't just set everything to low, ESC's do not work that way, they are trapezoidal wave generators, that is they control the motor with frequency. If you want to work out your PWM accurately, multiply the number of poles of your motor by the RPM it is running at and divide the total by 20. For example a 4 pole motor running at 40,000rpm has a commutation frequency of 8000, or 8Khz. If you had an 8 pole motor then the commutation frequency would double to 16Khz. As long as the frequency is close to the ESC's settings you will be fine.

Your Eflite fan will be running around 42-44K rpm and the motor is a 6 pole 3200Kv inrunner yes? This would give you a comm frequency of around 12-13Khz, so running at 12Khz will be fine, I would not go higher though as you risk generating more heat in the ESC.