I am running a fan on mine, but...the last time I was out on the track, I was running the MM with four caps attached to it running a 9XL geared 14/46 in my 8ight truggy on 4S lipo. At some point during my running on the track, the fan on the esc got bashed in and it wasn't working. After running for 30 minutes, the motor temped at just over 200 and the esc was at 150. When just playing around the esc will get to about 135 without the fan. With the fan, it gets to less than 120. When running the fan and on the track (30 minute practice sessions) the temps get to about 135-140.

I don't know if my results will be typical, but for me adding the caps made a difference. I believe that others have had similar results, but your mileage may vary.