My DS1 is 9 (10 in October). He's 31kg and 140cm. He is currently in a high-backed booster but he says it is getting uncomfortable (actually I think he is embarrassed by it - most of his friends now have no car seat at all, or some have booster cushions). I'm torn, I think I should keep him safe in the HBB as long as possible but I really do seem to be in the minority here. Can I ask what you do with similar aged children?