Somewhat related though not as huge of a factor of having scratchers or not, I had a doo XS chassis, and they are sensitive to rear spring settings. I think this was even in the manual and maybe mentioned cooling effect, doo wanted the snowflap bottom edge to be within a certain range from the trail. Given the molded curved shape of the snow flap, I think that has an effect of how the snow dust swirls up and recirculates back into the tunnel to help with cooling. I was in the UP once with another rider on a doo in the group and they were having temp light issues. Rider was on the lighter side and the torsion springs were set a little heavier, dropped a setting or two on the torsion spring block to lower the snow flap, still not dragging, and rest of the ride was fine.
I know not a major contributor like scratchers, but distance from snow flap to the trail surface when riding is a small factor.