We have pretty much the same dilemma. We observed the classrooms and talked to the older kids and the teachers and directors. There are definitely some great reputations and great outcomes in all schools.
We can choose between several schools - most of which subject accelerate later in the middle grades but which are pretty rigid in the early grades. One school does things a bit different and will accelerate early and often and the teachers work together to find the best fit. ( Interestingly enough, the latter school has had poor outcomes with kids in 3rd or higher coming in from publics, no matter how well prepared, starting at their current grade level. The kids have to be dropped back a grade to make it.) Going all the way through 12th is attractive, but once your kid gets to 5th, who knows what the path will be then?
At the end of the day, what goes on in the classroom is what matters and how engaged your child is within that class and how appropriate the material is for them.
You have to ask yourself, "What is a school?."
