May I recommend the book, "The Strong Willed Child," by James Dobson. Even if you are not Christian, I think you would gain insight from it. I had never thought of younger dd as "difficult" I'd thought she was "high-spirited" and that it was good that she was stubborn and strong-willed as when used for "good" these traits can carry you far in life

. However, used for "evil" they can make life very nasty. My dd2 started this backtalk thing too
I got the book. It was written about her! It doesn't make me see her as "difficult" just "different." Older dd responds so much differently to stimuli and to punishments. She would never DARE backtalk! Younger dd dares to see how far she can go. She doesn't care if she gets punished. The trick to dealing with her is to be totally impassive (which is HARD sometimes!) when I tell her she has done something she knows is unacceptable, so she has chosen to lose her TV priviledges for the day (week, whatever is appropriate). She wants that reaction of anger and she doens't care what consequenses she has to suffer to get it. So...no reaction = no reinforcement from the behavior. Of course, we still do "consequenses" but it's really made a difference to stay calm and almost bored sounding when we tell her she's done wrong. For some reason, strong-willed children fell powerful when they can make adults excited or angry.
I'm another one who can't STAND those cartoons where they talk so rudely. Angelica off the Rugrats...I can't even watch. It makes me nauseous. DD2 does not approach ANYTHING like that. My head would explode, book or no book!
Good luck with your DS. Positive reinforcement works better that any of the negative things, btw. Make a chart and for every day he isn't rude or disrespectful he gets a star. Agree in advance on what reward he will get for 5 stars, 10 stars, 50 stars, etc. Don't make the reward too far off or he will get discouraged. If he loses a star for the day, calmly remind him that he chose that behavior, now he won't get a star. This puts the responsibility on HIM to act the way he knows he should, instead of making it a power struggle between the two of you. In a power-struggle, both of you will always lose, every time
(as as a bright point, my strong-willed dd is my child who will come up and hug me and say "I love you" out of the blue, and can be soooo sweet. Everyone at school thinks she's quiet and reserved. They have no clue she's like Jeckle and Hyde!)
Laurie