My rotations have been fine, and I get to do as much as I want. Preceptor based is good for learning and being independent, and if you're on surgery or OBGYN, you usually get to first assist. Plus, you get more attention and guidance for preceptor based rotations. I'm planning on doing a wards based IM rotation during 4th year to see what it's like working in teams with residents and other medical students. Some of my classmates at the Birmingham site have done a few ward based rotations. My significant other has done majority ward based rotations at a MD school and says it's overrated and doesn't help you significantly during residency unless you were a poor performing student to begin with. But if you were doing a sub-internship in IM, that would be more helpful for intern year.
No, only about 10-15 students end up at SAMC for their rotations.