Summit brushless?

[himalaya]

You really need a sensored design if you want to do some crawling(what Summit was designed for).
Though MMM is the smoothest sensorless BL seen, but sensorless nature is right there, it's not possible to be comparable to sensored BLs in starting smoothness and driveability under extremly low speed. Uncountable start-brake-start-brake on the rock will drive you mad without a rotor position sensor.