Sounds like your school gets gifted kids. That's great! I would probably jump at the opportunity. My DS6 started full-day kindergarten at age 4 with subject acceleration 2-3 years higher still, and it has worked beautifully for us. However, he was also in a very small class (9 kids total), so the teacher could give him the extra attention a four year old needs, like help zipping his jacket, tying his shoes, etc. You might want to consider class size.