[blparent] Sensoring reading?

[Pipi]

Hey y'all,
After a conversation with a few people last night and this morning, I'm curious.
A bit of background: My nephew and I were watching Stand By Me last night. He said that he wanted to read the book. Red flags went up in my mind. He is 12. I know that he'd be fine reading half of Different Seasons, by Stephen King, which is where the novella of stand by me is, but I can't remember about the other half of the book. I think he'd enjoy shawshank redemption as well.
People I spoke to said they were reading IT and other Stephen King books at anywhere between 9 and 12. 
I remember still reading the baby sitter's club books at that age.
A friend pointed out that if my nephew wants to read the books badly enough, he'd find a way. I understand this point, but then think that he really wouldn't have the access to them.
His 2nd point was that as long as a kid is willing to discuss the books with someone and is openly talking, then it could be a great thing.
What are your opinions? Would you or do you allow your kids to read books above their age rating? Is this anything like sensoring TV and video games, or are books different?
Pipi