Another option which i am running and i know a few on this forum are doing is running a motor around the 1600kv - 1800kv on 5s lipo .

Even more efficient than running 4s and runs cooler and you get longer run time . 5S 5000 mah battery and you will get 20 mins for sure running a buggy around 40mph on a track .

Also you might also want to consider the Tekin R1 Pro esc , with a 35v capacitor added it runs 5s no problem , it is super smooth has great brakes and even though it costs more then the MMM it is tiny compared to the MMM