和儿子的争吵，关于handwriting

和儿子（１１年级）争吵了一晚上，我说handwriting会影响SAT essay grade，因为人都是有感情的，如一个essay刚刚好５分，如你的handwriting不好（但能认出来），就可能得４分，但他说，college board说了handwriting好不好（但能认出来）不会影响SAT essay grade，最后谁也说服不了谁，我们就达成协议贴到网上，如大家说他对，我就向他认错，以下是他在College Confidential forum的post:

How much does handwriting affect SAT essay grade?

Here is the scenario:

An SAT essay that is a clear 5 essay (from 1-6) is written by a student with average handwriting: legible, but not super clean/typed looking.
This essay is compared to an exact replica of the 5 essay, the exact same content and everything, except that this replica has an extremely clean, almost typed look.

When an SAT grader looks at these two essays, will the scores differ by one point, due to the neatness of the second essay?
For example, if the first essay received a 5, what are the chances that the second essay receives a 6 just because it had super clean handwriting?