Anfield primary vs. Beacon Hill

My son is now in Y2 at Anfield. Beacon Hill called a few days ago about an opening. Suppose he can get in Beacon Hill, I am going to struggle whether to transfer him.

We like Anfield so far. As it is new and small, the kids get more attention and the school is trying very hard. Beacon Hill, on the other hand, is well-established and big. We really need to figure out which one is better for my boy, but it is not easy as both have its pros and cons. Thus I would appreciate any suggestions or comments.

My son is a shy boy and usually shuts down in front of strangers. He's smart and a good student though. Also he's a natural athlete.