It also states that 1500 RPM and moving. All the RPM increase does is charge the battery and give good current to the pump motors. It is the moving in the water that gives a little push to the water.
I have the x-15 (2011) and just listen to the motors & see water over the side. The blinking lights are useless. When emptying, you can hear the motors get loud and you will also hear "bubbles" from under the boat.
I have filled / emptied the boat numerous time without the motor running.