I revised my blog post on the topic http://historical-jesus.info/53.html. I even quoted you. I hope you don't mind. If you do, I can paraphrase your quote. And I got 2 arguments relative to the epistles http://historical-jesus.info/73.html.(Bernard, I know you will not agree with any of the indicators I have posted recently, since they lean toward Marcionite priority; but do you know of any other examples for Marcionite posteriority? You have given 2 so far, I think, and I have added 1. But, if there are more, I would love to have them.)
All these arguments are mostly or totally independent of: if gMarcion is witnessed to have changes or deletions which can be explained by Marcion stated beliefs, then that means Marcion worked from gLuke, even if Marcionism would explain the differences between gLuke and gMarcion. But even the later can be justified as a method to affirm the posteriority of gMarcion, because Tertullian in AM defined Marcion's Christian tenets through Marcion's own Antitheses before analyzing the Evangelion, which would avoid the argument: we know Marcion's teaching through his Evangelion and the Evangelion tells about Marcion's teaching (a circular argument). Instead: we know Marcion's teaching through his Antitheses and the Evangelion reflects the Antitheses and gLuke (not a circular argument).
And gLuke theology and christology is not much different of the ones of gMatthew (except for the level of Judaism in them). So I do not see why gLuke should be considered a reaction to gMarcion, when gMatthew is not.
I think we have enough evidence gLuke was written in the first century, which would make Marcion copying on gLuke: http://historical-jesus.info/62.html.
BTW, gMatthew, better than gLuke, can be dated 1st century (http://historical-jesus.info/53.html).
And Q as a separate document and "Luke" not knowing gMatthew: http://historical-jesus.info/q.html and even the complete gMark (the great omission http://historical-jesus.info/appf.html).
All of that add up support to the posteriority of gMarcion. And I did not develop these web pages in order to prove the posteriority of gMarcion.
You might think 5 arguments drawn from the Evangelion are not enough, but certainly Marcion did not want to give indication his gospel was written late (as for the other synoptic authors) and certainly not later than gLuke.
By the way, I found all your arguments for posteriority of gLuke very weak.
Cordially, Bernard