Hi Pie in the Sky,
I suppose I should ask how many school moves already?
To be honest DS1 was ok but by the time he goes to senior school he will have done the maximum 5 years at his prep and he should do the maximum 5 years at his senior school so apart from an unsettled start he will be doing what most boarding prep educated children do. Although never ideal I think moving when they are very young does not have the same impact as when they get to Yr4+.
However, we are really struggling with DS2 who has had many moves too. I fully intend for him to stay at his current school until Yr8 eventhough I have a number of concerns and he is not doing very well this term. I have often been hasty and pulled them out but with hindsight I should have either chosen more wisely from the start or tried to work with the school more. Some schools you can work with, others you can't!
It also depends on your goals. If you want a specific senior school then find a feeder and keep them there. If you are worried about academics then this will probably cause you a lot of stress so better to move them than become more and more frustrated, but make sure you pick the right school so the same issues do not occur. Often the niggles are more to do with our expectations than the school. And all private schools are flawed - if you go in with that attitude then generally one is pleasantly surprised when good things happen, which is often!
But after today I would definitely tell you to have open dialogue with the school and especially with teachers you may have a problem with!