I just did three of them for my kids all under 13. I think it only wants parental controls disabled so you can access the internet once your on 2.1. I had no issues. I disabled all the restrictions it would let me before downgrading, then reenabled them once I restored. The only thing is that all the homebrew apps on the home menu ask for a pin before using them but since he's 6 you probably don't want him using them any way. So just disable what you can before down grading and it will be fine.