While braking energy is stored back to the battery.
Take a look at this graph for example
While decelerating Amps do rise as do voltage (comparable to recharging your batteries). As long as you do not apply throttle and your motor is still revving energy is stored back. The amount of energy depends on how hard you brake and seems to be "proportional" to motor RPM when you let off your brakes.
So yes, if you use ESC brakes runtime will increase somewhat.