This topic has been discussed many times on this forum...

The one thing I would suggest, is that if there are alot of young BBs, it will inevitably mean that there are alot of young students. This is fine if they are in separate classes, but if the classes are integrated, then it might be fustrating for adults.

Otherwise, use your instincts- are the BBs in your oppinion worthy of being BBs. This gut instinct will probably be far more usefeul in deciding the worthiness of a school, than us debating whether or not young BBs are a sign of a McDojo or not.