We were in the same boat, but our school district told us that ds would not be able to attend private kindy and "skip" into first grade. They would send him back to repeat kindergarten, despite the fact that he was advanced across the board. That set us on the road to homeschooling, an option which is still working beautifully for us eight years later.

I think schools need to become more flexible, or they risk losing more of the best students.