Advisors are great, and the resources on this forum are great, but do the research for yourself and find out. SMPs are a huge risk. Some things to consider: Have your grades been mostly A's in upperdivision science courses for at least a year? Have you taken any courses on cell biology, physiology, biochemistry, or neuroscience (typical medical SMP classes) and have done well?
Even if you answer yes to the above, you still might not do well in an SMP because B's HURT. in fact, you must be able to HONOR your med school classes. go to the allopathic or osteopathic forum and poke around to see how hard it is for students to honor a class or block.
I'm not saying this to scare you. Many people like you probably have done this successfully. But for you, it may be a big unnecessary risk: you may get accepted to medical school if you improve your application in other ways.
Like I said, a hard master's in the biological sciences, IMO, may be more beneficial. The grades won't count but your MCAT and your GPA are aleady pretty good. You will have more research opportunities. You will have great LORs because you will be working closely with faculty. And you will have more time to do other extracirricular activities. If you do some clinical experience while working on your masters, say volunteering at a hospital once a week for a year, you'll be improving in almost all ways of your application except your GPA and MCAT.
