I'm someone who commented on the other thread because we have deferred our 31st august son.
Aside from the emotional side of things how do you think your child would fit in other wise? These are the factors we took into account when deciding on whether or not to hold him back:
-he has a slightly speech delay due to glue ear as a toddler, he can talk but a lot of things are still mispronounced and he is often difficult to understand, speech therapy said he wasn't bad enough to need treatment but the school agreed he would struggle to be understood in a loud classroom environment but other children and the teacher.
-he still struggles to dress himself, still often needs help to clean up after going to the toilet.
Emotionally he's probably in a place where he would have been fine at school, he thrives socially and makes friends easily, but those issues and his age we decided to hold him back. Someone mentioned the child having to go into year 8 once starting secondary school, we were told this too but it depends on school and area, I checked and here that's not the case.
We have an older summer born who is now going into year 2, even though he is one of the youngest he is ahead of the curve academically and is extremely bright, we would never have considered deferring him as we knew he was ready for school, but his brother is a completely different story!
The school is notoriously known for not allowing pupils to defer places and have know many people from pre school who had tried to and weren't allowed so changed the school so they could defer their child, so the fact that the school did multiple assessments of him and agreed that he wasn't in a place to start cemented our decision!
From what I remember of ds1 starting school there were quite a few kids who were very emotional for a long time going into school, lots of crying and and parents agonising saying they were refusing to go etc, that all resolved very quickly and those children turned into very happy members of the class very quickly!