My son is 7 1/2 yrs old, and slightly above average in height and weight. He currently rides in a HBB, but now that he sees all of his friends in NBB or in some cases, no boosters at all, he is asking to switch his seat. For daily rides around town, would he be okay in a NBB? We would use the high back if we were going on any sort of long trip where I thought he might fall asleep. He has been riding in a booster since he was 5, and sits fine in it. He understands he has to sit in some sort of booster for a LONG time still, so he is not asking to go without anything. He just wants to get rid of the top part.