Hi, Shufflex,
In your hypothesis, if the teeth are facing the rear you are cutting on the up-stroke.
I do not think turning the blade toward the front or the rear changes the cutting motion.
I believe the blade is still cutting on the down-stroke.
If, however, you turn the blade up-side down, THEN I think the cutting action would be
on the up-stroke but, I think most scrollers here would concede that it is harder to control the
wood because it would continually want to pull away from the table rather than being pulled into
the table as it is cutting.
God Bless! Spirithorse