So when i switched Shadow to Canidae I was going to go grain free but the lady at the store told me that since he is a puppy we should go with the All Life Stages formula instead because as a puppy he needs the grain nutrients. So I bought the All Life Stages and decided to wait for grain free till he is about a year old (He is about 13-14 weeks now). Was the lady at the store correct? What's the benefits of grain free? Are there benefits of not going grain free?