im really not sure how hard it is to get in. im sure each year it gets more competitive. i had a friend who didnt have the minimum mcat req and was denied. i think they are looking for the ones with the best chance to succeed, and by the ECs and essay at how well you will do in front of an adcom (dr.mulroney is on the g-town adcom and is one of the main profs involved in SMP)
i think if you are really sure this is what you want to do, but still have some concerns, you should try to contact dr.myers (the SMP head) and let him know how interested in this you are. he is a really nice guy and will tell it like it is.
i had a 3.25 undergrad (3.15 BCPM), double-major, and 29Q when i applied to the SMP.
i finished with a 3.37 in the SMP getting all A's in grad classes and B/B+ in the med classes (lol, i thought my gpa was higher but i just checked it) and got in the year after i finished the program.
on their website you can see what happened to the class (how many went to what school) although it doesnt look updated since we graduated, may just be the ones who were accepted at the end of that class year
link to SMP page with lots of Info.
link to message forums that the SMP profs, students, and applicants can talk on
edit: i just found this post from dr.myers that sorta answers your question
"We consider everything, and how much we consider a particular item will depend on what that item is, and how remarkable it is. In general, I would say that the next two common factors are the undergrad school and major, and the trend in grades. But to illustrate my first point, if the letters are not strong, they would become a dominant issue."
"About 500 students are expected to apply this year."
and it is designed as an 11month program, but we all finished by mid june time frame as the only class in the summer is just your final research paper which most of us got done ASAP