I have been through all of this; and would like to share my experience here. We shifted our children from a decent state school to one of the country's top private prep schools while they were in Year 2 and 3. We were not filthy rich, but we thought we could afford it. In between we had to move, but then we went into another top private school.
Eventually, they made it rather automatically to the private secondary school last year; but to my utter surprise, so did many of their friends from their state school, who have now joined them. I was still in touch with some of the mums, though the kids had moved on.
Of course, rest of the story is unique to me, I hope none of you go through this. We are in deep trouble now, because my husband had some issues at work, and we are now unable to fund their private secondary school. We had to sell our house at a huge loss and downsize, and are in deep trouble overall. My husband did manage to find work, but his bonuses have gone down. Little did we realise that for sending two children to private school, even an investment banker with a working wife would struggle.
I feel we spent a fortune, but at the wrong level. If we had kept that money, we could have educated them well in secondary, where the difference really shows, instead of wasting it at primary stage.
Of course, children had lots of fun, the games they played were more expensive than in their state school, and arguably more stylish. Their friends are more posh and privilaged; and they think they are now elite; difficult for them to mingle with people who has less money. Again, I am not generalising here, this is just my experience. In a nutshell, I feel they are less prepared for facing life today.
Overall, I wish I could rewind the clock and keep them in state primary atleast till they are 10 or 11, and moved them to private in secondary or just a year earlier.