Probably the biggest advantage in training with a lot of people, like at my school for instance, is that you get a feel for different types of people, you know what I mean? In a bigger school you'll have people of all shapes, sizes, and strength...so...in that sense it would be better than in a smaller school. However...I prefer smaller schools...though one REALLY, REALLLY, REALLLY bad thing that can happen at a small school (which I have experienced mind you) is the "clique" or "cult attitude." This happens when it's only like 5-8 people in a dojo and they're all black belts so they just train and work out and talk with each other so much that when a new student comes in to learn...especially if they have some experience with other arts (after they ask you if you have experience with other arts mind you) they want to talk down to you and they have this really nasty, negative "I don't want to teach you or anyone else that's new" attitude. I had that experience within my OWN dojo!!! My dojo shares Aikido and Judo on tuesdays, thursdays, and Saturdays. They do Tae Kwon Do on Mondays and Wednesdays and Dan Zan Ryu Jujitsu also on Mondays and Wednesdays. It was the Dan Zan Ryu Jujitsu group (which is very small and they're all black belts [as well as the TKD group] ) that I had this negative experience. However...thanks to my faith in Christ, first and foremost, and my limited Aikido training I handled it well.