Well you can take it from an expert that when Magoo starts the too hard biting we pull out the toy! I really think Dylan is playing and he is just relaxed enough with you that he thinks he can play rough. When it starts to get rough remove your hand and throw in the toy on a string and let him attack that. He is probably confused as to why you don't want to play with him when he is just treating you like a kitty friend. He will learn that the toy is for such biting.
Believe me when I tell you that the sweet and adorable Peanut Butter wants to play it can hurt! I know he means no harm but that doesn't stop the pain. I do him the same way. Then he gets to play with mommy and I don't get hurt!
I hope this works for you.