In our situation, SD was 9 at the time, and her expressed opinion was initially given weight. Unfortunately, as STIDW says, the rationale of what she said was misunderstood and she was in any case unwilling to be honest about what she wanted. She was very miserable around her mother, but once it was explained to her that her mother would know what she'd said, she felt unable to express that, so said she wanted to live with her father from Friday to Monday and her mother Tuesday to Thursday. Her rationale for this was that as far as she was concerned, this would mean seeing the least of her mother, because she was at school on those days, but sounded as if she liked them both the same. (This was anyway what she told DH, with whom she was living during the case.) CAFCASS, in the interim report, and the judge interpreted this as her wanting to live with her mother and spend weekends with her dad, which was hugely frustrating. It also led to her mother being given daily weekly contact for several months as the case limped on, which caused SD to become severely distressed.
Her views were never revisited, even though she told DH that she wanted to explain again, almost a year on, that she really wanted to live with him. In the end, the concerns of the authorities about her mother's parenting were so great that the final CAFCASS report was 'unable' to consider her 'wishes'. Her distress at the idea of living with her mother by this point was so great that we were very worried that she would ever find out, if it happened, that it was supposedly at her wish that residency was awarded to her mother.
Sorry to go on, but it's a bit complicated. Essentially though we were surprised at how much weight was initially given to her opinion at such a young age, and how little effort was made by CAFCASS in interpreting it. The CAFCASS officer was very reluctant to consider a solicitor and guardian for the children, despite the incredibly high levels of hostility that the ex demonstrated to DH, regularly occuring in front of the children and even the CAFCASS officer herself.