My son has been reading Calvin and Hobbes on and off since kindergarten. He just went through a phase where he whipped through a whole bunch of them again. We can't sensor either. It just wouldn't work at our house and all the content we've come across seems to be ok for DS8. My husband actually owns almost every C&H book published if that says something about him!
It's interesting some of the cultural and historical discussions that have come up due to him reading C&H. And changing with his age and maturity level too.
