The IMS program is about 15 people who take classes along with the USF MCOM students. It's slightly more difficult to get into and you'll definitely need to apply early for it. From what I hear, as long as you do well in the IMS program, you stand a good chance at getting into USF MCOM. I couldn't give you an exact number of IMS students who get in after they finish the program but I would say that as long as you do well, you have a great chance at getting in.
I'm in the MSMS (Masters in Medical Sciences) pre-professional program. There's about 250 +/- students in this program. From what I heard from the students last year, about 10-15 were accepted to USF MCOM immediately after finishing the program. As far as getting accepted the year after you finish, when you have the final transcripts to show how you did in the program, I couldn't tell you how many have gotten in since the advisor doesn't keep those statistics for some reason.
The IMS program is based on the USF MCOM curriculum, which I believe is an integrated systems approach with block scheduling. Since they take classes with the med students, their performance is graded based on how they compare to the med school class.
The MSMS program is not systems based and the classes are 2-5pm, M-R. The material we cover is broader than that of the IMS students. We cover the first 2 years of the average med school curriculum based on subjects, not systems. However, despite the vast amount of information we learn, we do not necessarily go into as much detail as the IMS students. (This is just anecdotal, but many IMS and USF MCOM students have said that the MSMS students study more than they (the IMS and med students) do.) Our classes this semester are Anatomy, Biochemistry, Genetics and Immunology/Microbiology. Next semester is Neurology, Physiology, Pharmacology and Histology. You also have the option of taking an MCAT prep course worth 2 credits in the MSMS program.
The MSMS is a good program, much like I'd imagine most other SMP's are, but as you may imagine with a class of 250, the advising is sub-par.
With the IMS, however, I believe you will get much more attention from advisors of the program, as well as professors from USF MCOM and likely even the admissions committee while you are there. (This is just speculation though)
Hope this helps! Let me know if I can answer anything else.