My past experience with many types of electric motors, both brush-less and brushed, DC/AC has shown that properly regulated they can provide INSTANT torque. Modern electric wheelchairs use brush-less, gear-less motors that provide maximum torque instantly, in fact they have to be detuned to protect the operator from extreme acceleration. We've even set them up for experienced users to be able to pull wheelies. I use only brushless electric motors in my race RC's, and they can spool up so fast as to be uncontrollable. Sophisticated digital speed controls are a must.
I'm sure the electric motors in this application are more than up to the task for short duration boosting.

Yep the outrunner brushless motors are awesome torque monsters. I fly R/C heli's and pylon racers running Neu in-line motors and Castle speed controllers, nothing like controlling a flying welding system.....LOL Running some ridiculous power levels with my F5B style planes, 2-3 kilowatts running the motors for 5-10 second bursts max!