UPDATE October 2012, after a year and a term back in the States: Everything I have written about Hill House's superior education below, I believe even more firmly now. The foundational education that my son received in three years of Hill House eclipses the foundation his sisters have received here. My eldest daughter did kindergarten back to back, reception at Hill House and kindergarten in Texas, and the difference was stark as well as discouraging. The fault line is not US v UK academic instruction, though the UK is not as in thrall to early academic testing that has eviscerated US early education. The fault line lies on how we teach children. We don't educate children. We teach them to complete tasks. The lucky children are the ones taught to complete those tasks themselves. I will revisit most of these issues in articles at PJMedia (I'm now a freelance writer) starting with an upcoming review of Camille Paglia's Glittering Images. It is a remedial art history book that she wrote for homeschooling parents so that they could provide the rich education that we were fortunate to have for a few years in London.
The short take: We moved back to Houston because our entire family, both sides, lives here. Yet despite such significant ties, every day I question whether I have done the right thing by my children in moving home and leaving Hill House. I knew the school was a rare gem while I was there. I really had no idea how much of an oasis from modern parenting chaos it was until I had to go somewhere else.