We have adopted an older U2 recently, and have enjoyed him immensely. He is challenging at times, but not as bad as we expected. I saw some babies at a pet store this week, still being hand fed, and their future owners were there visiting. They were snuggling it, petting it all over, treating it like a puppy. I would think that it's probably important not to set up habits with a baby that you don't want as an adult. I think that any information you can learn about an adult cockatoo will help you a lot, as from what I've read and seen, babies are marvelous most of the time, but you need to understand what they are like once they hit sexual maturity, and work to prevent future problems.
Our cockatoo does a great job of being independent, I think the training we've done to teach him to stay on his stand has helped a lot. Plus LOTS of toys. We must spend at least $20 a week on toys or supplies, plus lots of home made ones. He's a better birdie when he's busy!
We're also working with a trainer named Pamela Clark. She helps people all over the world using video chats, and it has been life changing for us and our bird.
Good luck with your decision!!