It will really depend on the use of reverse thrust. Without reverse thrust, both settings will result in the same amount of energy being absorbed. However, the min brake setting will absorb the energy over a slightly longer period of time. The end result will be the min setting will result in slightly cooler brakes.
If "judicious" reverse thrust is used, at higher speeds, the reverse thrust will be more effective than min brakes, so no braking will be applied. With med, you will probably get some braking at higher speeds. Net result is higher brake temps using med auto brakes.
IIRC, there is a chart in the performance manual that talks about auto brakes and max reverse thrust.