So, having been a high school racing coach for 23 years, I don’t think the answer has much to do with the free fall discussions above. Here are my thoughts.
1. During a straight, gliding section of a race course, the heavier rider has the advantage. He/she will overcome the friction caused by wind resistance and snow much better.
2. However, in turns, the lighter, more agile rider clearly has an advantage. Since a race course is mostly turns, smaller riders tend to have an advantage. Can’t even count how many times a 12 year old has beaten me just because they can go straighter down the course.
3. Of course the largest determinant is how well the rider holds their edge and holds their line through the course. The more talented rider always wins.
Paul