It depends on the size of the school---since there are so many more allopathic schools, they have a wider ranging class sizes and so you have to take that into account. I think the smallest class size of the osteopathic schools is OSU-COM at 88, correct? I know at DMU, class size averages from 190-210, depending on the applicant pool that year. But I never found to hard to corner a professor for a personal question or get my emails answered promptly. I guess that is the benefit of a private school with a student-centered mission. I think you will find other schools to have similar responses. I applied to both allo and osteo two years ago and found that it isn't the faculty/student ratio but the attitude of the faculty and whether they are there to help you learn or not.