Since everyone hears differently there are many different outcomes. Yes, CI kids are HOH, although some do much better than others. The key to your above post is you seem to be talking about those who are implanted post lingual. However, the children who receive their CI before the age of two do much better than those who receive theirs after the age of two. There is also a huge difference between success rates in those that are post lingually deafened and those who are pre lingually deaf and received a CI later in life. I know a number of people who have CI's and those that were post lingually deafened do much, much better than those who were born deaf. One friend gradually went deaf and had his first implant in his mid thirties. He did so well he decided to go for the second implant and if you couldn't see the processors you probably wouldn't know he is deaf without them on. Another friend received his in his early 60's after a lifetime in the aircraft industry left him profoundly deaf and unable to get any measurable help with HA's. He too went for the second implant after seeing how well he adapted to the first one. He can carry on a normal conversation and talk on the phone without any problems. The only complaint he has is: once he takes the processors off, he is completely deaf. I know others, including some children, but I won't bore you with the details.
Time will tell if this study has merit and we will just have to wait and see what peer review studies reveal as to the validity of this one.
http://www.lsl.usu.edu/files/fryauf-bertschy-cochlearimplant.pdf