The difference between the sintered rotor and the standard bonded rotor are the way that they are made.
The sintered rotor is made in such a way that it is a much higher magnetic strength densitiy and it has much better heat tollerance characteristics than the bonded rotor.
The bonded rotor has some other matierals in it that allow it to be more easily manufactured, but these materials detract not only from the magnetic strength of the rotor, but also from the heat tollerance of the rotor.
What will you see in your car?
First off the sintered rotor will feel like it has a lot more magnet than the stock rotor. It should actually cog and resist you pushing on the spur gear whereas the standard rotors offer very little resistance.
This added magnetic strength will allow you to pull taller gears more efficiently than the stock rotor all while being more efficient and creating less heat in the system.
You should also experience more drag brake and more "natural" slowing down of the car that should be more comparable with the feel of a brushed motor.
Going fast is important in racing...but so is being able to slow down!!
Hope this helps answer your questions paco!