Its not just the instant power. A/C brushless style motors are more reliable, less parts to fail, less moving parts, thus less heat, thus also more consistent power.

Brushes eventually fail, and the motor has to be taken apart and the brushes replaced. Brushes also dirty the armature which means less and less power...unless you take the motor apart and clean the armature.

My guess is that brushed motors in this sport will probably eventually disappear except as really cheapo applications to entice you into the sport. Brushless motors are actually cheaper to make from a manufacturing standpoint...of course, less failures so they can't sell you a new one in a year.