The controller can turn devices on and off such as any random powerhead. The aquasurf with a controllable tunze pump can do a bunch more like 30% 100% pulses, Wave mode (like having a wavebox in your tank) etc...
The problem with turning AC pumps on and off is they are prone to failure and maybe not starting back up again, or starting up again with the propeller going the wrong direction...
With the controllable Tunze pumps I listed above they are meant to be controlled like this and won't have the start up problems