Preschool isn't an academic preparation for kindergarten, so I am not concerned about your three-year-old being "above" or "below" the others in his preschool class. It's asking a lot of three-year-old to adjust to his mommy being his preschool teacher. It's unfair to assume that he has the emotional or social development necessary at this age to distinguish between "Mommy at home" and "Mommy as teacher."

I don't believe that you would be doing him serious harm by continuing to keep him in the preschool where you teach, but I would elect to place him in another fine preschool program. In a preschool setting without you present as a teacher, he will be unencumbered by the conflicts that your daily presence in his school presents. He will learn to separate naturally from you and to socialize and learn on his own, without the omnipresence of his mom. He will also get the opportunity to interact with other kids as his "own person", not as "the teacher's kid." This social opportunity will afford him more of a chance to establish his own sense of autonomy and independence.

Don't be surprised if this transition to another school is a difficult one. After all, you have established a pattern of never being apart from one another and his experience of preschool is one where mommy is always present. I would transition to the new preschool with the usual visits so that he can gradually accustom himself to the move. I'm sure that this change will benefit his overall development.