I went to a medium size program 36 residents. Here are my thoughts
Pros:
1. more intimate/more facetime with attendings
2. Usually very flexible because they generally don't rely on residents as much as bigger programs. I disagree with the other posters on this point. I have friends that went to programs with <5 residents per year and they had very favorable schedules.
3. More perks ie moving expenses, paid CME, big book allowances
4. More time to read about patients
Cons:
1. Small volume
2. Often lack diversity of subspecialists (but not always)
3. Many programs are plagued with "private" patients which are followed by their primary doc. This is good, because you meet the people in the community, but it is bad if they don't want to educate or meet you.
4. Many times you do have to send away your most interesting patients.
+/- Usually more prepared for primary care than subspecialty care
My thoughts