From talking to admissions officers at the University of Chicago and at other medical schools, there is no significant advantage. ED is just there for students who the med school knows well and who would like to accept early in the application process. Its a risky affair because ED is binding, you can't apply anywhere else. And you don't find out if you've gotten accepted/rejected usually till October. By then your late in the application process for submitting the AMCAS. So I'd have to suggest that you avoid ED.