About the Episode of the Independent Exorcist (personally I like a lot it!), I was wondering why Marcion would have removed it, assuming the traditional model (Mark ---> Mcn).
(Mark 9:38-41)38 “Teacher,” said John, “we saw someone driving out demons in your name and we told him to stop, because he was not one of us.”
39 “Do not stop him,” Jesus said. “For no one who does a miracle in my name can in the next moment say anything bad about me, 40 for whoever is not against us is for us. 41 Truly I tell you, anyone who gives you a cup of water in my name because you belong to the Messiah will certainly not lose their reward.
What I see is that the episode is implicitly anti-pauline, and not philo-pauline as generally considered.
The answer of Jesus to John seems to predict that only at the present time the Independent Exorcist is doing good things in the name of Jesus: really, in a next moment he will say something bad about Jesus.
In Mark 13:6 Jesus predicts the arrival of Christ-emulators who are very similar in behavior to the Independent Exorcist:
Therefore Jesus says ''dont' stop him'' meaning only at the present time. In the future the Independent Exorcist will cease to be a positive figure, to become rather an impostor, or worse, a ''Jesuophobe'' (a despiser of the body of Jesus, i.e. a docetic Christian).Many will come in my name, claiming, ‘I am he,’ and will deceive many.
The function of ''stopping'' the Independent Exorcist is very surprisingly similar to the enigmatic figure of the kathecon, who stops the Anti-Christ.
2 Thessalonians 2:6-7
So the Jesus of Mark is predicting that the Independent Exorcist will become a day his enemy, and an enemy of the his disciples (so also of John son of Zebedee).6 And now you know what is holding him back, so that he may be revealed at the proper time. 7 For the secret power of lawlessness is already at work; but the one who now holds it back will continue to do so till he is taken out of the way.
Now, the problem is that
1) if the Independent Exorcist is Paul or a pauline figure, and
2) if Marcion is known to brandish Paul as the only True Apostle
...then the reason for Marcion to remove the episode of the Independent Exorcist from the his Gospel coincides with the same reason why Mark would have to insert it in the his Gospel: to attack the Independence of Marcion's Paul from the Catholic Church.
So it is more probable that Mark inserted the episode of the Independent Exorcist in reaction to Marcion's Paul than not the contrary (that Marcion removed the episode of the Independent Exorcist because he realized his anti-pauline and anti-gnostic nature).