The evidence you're referring to is actually in reference to late deafened adults -- not children.
Research has proven time and time again that children who are implanted before the age of 5 receive the most benefit from a CI.
In other words, the earlier the better.
No, I'm refering to deaf people who were born with useful hearing which deteriated over time. Also I am refering to totally blind CI users. I read an article once from a totally blind bilateral CI user who said that the parts of his brain that normally dealt with vision had taken over making sense of what he got from his CI.
Put it this way. I know about 5 sighted deaf who stop wearing their CI. I don't know any blind CI users who have done that.
Why cancel out experiences from late deafened anyway. Isnt' that a big enough market?