The 599 and 9930 are very close in torque, the big difference is a brushless motor costs more and is initially quicker from the start, whereas the coreless is smoother from the center as it moves better for fast flying planes. I have flown coreless decades ago and prefer them to the bigger 599 brushless in jets they are more twitchy, and need a lot more expo to smooth it out. That's just my preference.