Well, one big pro is knowing early, which can greatly reduce the stress. I cannot emphasize enough how good it felt to know that DS was actually going to college with a solid acceptance. Also, since we were on the hunt for significant merit aid, he was in consideration for the full range of financial aid, including competitive scholarships that required additional essays and applications.
The only con I can see is that if he grades or test scores could benefit from another testing date or grading period it is better to wait.
For your school specifically, it appears that the Monroe Scholarship (full-tuition) picks its applicants only from Early Action, so if you are looking for merit aid and believe your D to be a highly qualified candidate, then waiting could deprive you of participation in the competition for the award. http://www.westmont.edu/admissions/#...holarship.html