KFDancer, may I ask why you're moving back? Is it a work thing or is there some reason you don't want to stay in the UK for school years?
We prefer the US education system to the UK system. My husband is certainly a success story of the UK system though.
Mine are still young (3 year old girl, 5 week old boy). A lot will depend on what kind of students they are. The UK system is exam based, so you MUST be a good test taker to excel here. Also the pressure to know what you want to be when you grow up at a very young age. This path is then the path! I had no clue that I would be doing the job I do now at 16. If I had to pick back then, I wouldn't have made the right choice.
The US system is more forgiving. If you aren't a good test taker but are good at papers, presentations, projects, and participation, you can still do well. Also there are so many paths to a university degree (community college, acceptance of more "mature" students, easy to go back to school in later years if desired). And the cost. I just looked it up and a 4 year degree at the school I went to is $17k. Three years in the U.K. is £27k!
Our plans could certainly change but as of right now, we plan to be in the US prior to the start of secondary school.
I also think they start too young here. On a local group, people frequently ask for tutors for their 5 and 6 year olds. In my opinion, those kids should be playing and in after school activities, not buried in books worried about math!
Like I said, I know many many success stories with the UK system. But you've got to fit the mold. I really hope my kids don't have special needs, otherwise we'll definitely need to go back. I would not have done well here (but am very successful due to the US system). Needless to say this is just my opinion and not fact!