I'm currently a student in the MBS program at Tufts.
The program is pretty rigorous. During the fall semester, we had 16 units with 4 classes being first year med student courses (Molecular Biology, Biochem, "Cell, Tissue, and Organ Biology" (histology), and Immunology). All of the courses with the exception of Immuno were taught by the same professors (90+% of the time) as the med students, just later in the day. Immuno was telecasted for the MBS students. The telecast wasn't too bad. The room they use for that (computer lab) is in the same building and we had a TA with us to answer questions. The only MBS specific course was "Intro to Clinical Medicine" and it wasn't terrible.
The Spring semester is a good bit tougher. It's 19 units (including a 4 unit(s) (of) elective(s) [some electives are only 2 units, but you need 4 to finish]) and the only med student course is Physiology. The other courses either closely mirror, or seem that they will (classes are on a block schedule, so we've only started Anatomy and Physio so far), the med student cirriculum. The "non" med student courses are anatomy (different because there isn't a cadaver lab for the MBS students), pathology (haven't started yet), and nutrition (Med students took this in the fall).
The program is linked with their MPH program so that you can complete an MPH during the application year. The only caveats to this is that you have to take Epidemiology for your elective and you can't do a lab thesis (time frame).
The program does require a thesis for graduation (you can opt for a "certificate of completion" instead, though). The thesis can either be a lab or library thesis and the details (financial aid? length of thesis?) are still being hammered out.
The program is graded on a letter scale and the curve is based off of the med student's performance. There has been very little difference between the means of the medical students and the MBS students though (but we did beat them in Histology by 2 percentage points). For the classes that are the same as the medical students (Biochem, Molecular Bio, Histo, Physio, Immuno), the tests are exactly the same and given at the same time as the medical students. The unfortunate side affect of this is having a month of classes starting at 1pm and the test at 9am.
Every student in the program does get a faculty adviser, but they are not necessarily MDs. As well, the program does provide a composite letter at the end of the program for medical schools. They have told us that you can add letters from undergrad if you want to (strong academic or research letters, for example) and they will either incorporate the LOR into the composite or mail it with the composite.
You will not be able to work during the program. First, working will detract from much needed study time. Most of the exams have averaged in the mid to upper 90 percent range. This makes recovering from a bad exam painful to impossible. Second, the class times switch from week to week. You won't have class starting and getting out at the same times every week.
