I was in your boat a few years ago. I was a bio major and had a 2.9 cumulative GPA and around 2.9 for my sci GPA. I graduated in 2005, did what was basically an SMP in 2006, and got into medical school (MCV) that year (no glide year).
The opinions on whether to do a undergrad-level postbac program or an SMP differ mainly on how people weigh the undergraduate GPA. Many, especially from the west coast, say that your best bet will be to take Ugrad classes and pull up the GPA. With a low GPA, however, it will take a significant amount of classes to do that. Let's say that you graduated with 120 credits at a 3.3. To pull that up to a 3.5 you need to take 48 credits and get a 4.0 in all of them.
If you began with a 2.9 you have to take 144 credits to raise the GPA to 3.5. That is another 4.5 years of Ugrad taking 16 credits a semester!
I do not agree with this, especially for people who were science majors. If you have already taken the pre-recs and science classes higher than the prerecs, why would you take a step back down to the 200-level? Your application should be moving forward and improving at every step of the way. You should not be going backward. An SMP will allow you to move forward by taking graduate level courses.
The best thing that SMPs offer is a distinct line between the 'undergrad you' who had crappy grades, and the 'graduate school you' who will hopefully knock the program out of the park. By making this distinct line, you are penalized less for poor grades. Ugrad grades become less of an issue as it is easier to distinguish yourself from your early college carrer and show how you have matured and grown as a student. These programs are also designed to get people with lack-luster numbers into medical school. They are designed with people like you in mind.
Some things to consider: generally these programs are really hard. If you don't come prepared you will get demolished. If you get demolished you won't ever get into medical school.
How much they cost: some programs are really expensive and others are not.
What medical school the program is assocaited with?: If the SMP does not have an associated medical school, don't go there (ie Georgetown SMP has georgetown med school but the American U post-bac program does not have its own medical school). Your best bet is to get into the medical school associated with the SMP so pick your SMP accordingly.
Figure out the numbers: what is the rate of acceptance to medical school from these programs?
From my experience on the east coast, the SMPs are recommended for people who have done the pre-recs and the post-bacs are recommended for people who were not science majors or have not taken the prerecs.
Word to the wise: don't take advice from people who are a few years out of college and are still not in medical school. Apparently what they are doing is not working.
