Fast speed at most times is too fast. If you slow it down a bit it drags across the glass. Its hard to explain. It just doesn't sweep nicely across the glass. Besides, with a three speed motor I think that I can add a delay timer unit on it. I know that the two speed motor is completely different and the wiring is too. I am thinking that the variable speed and the three speed motors are the same. Just the switch and the connections are different. At least thats what I think.
I was hoping that someone can confirm that.