If at all, it only decreases ur chances of getting in because schools don't give u any preference in EDP, and then since u r late in the application process, it decreases ur chances of getting in elsewhere.
I was thinking about EDP for a long time, and then gave up the idea.
EDP would help if u wanna go into a school with an avg. MCAT score of 30 when ur MCAT score is 35-36 and ur GPA is sig higher too, because it is very likely that u will get in (unless u screw up ur interview, which u might because it's ur first). That is a very good way to save lot of money!