Recently one of my favorite scholars, Mark Goodacre, appeared on the podcast MythVision to discuss the Q source with Dennis MacDonald. Goodacre is famous for his repudiation of Q, discussed some in his book The Synoptic Problem: A Way Through the Maze (T&T Clark, 2001) and at length in The Case Against Q (Trinity Press International, 2002), both of which I highly recommend. MacDonald is a noted scholar as well having written a number of books connecting New Testament literature with classical literature, for example his book The Homeric Epics and the Gospel of Mark (Yale University Press, 2000).
The discussion itself revolved in part around MacDonald’s view, proposed in his book Two Shipwrecked Gospels: The Logoi of Jesus and Papias’ Expositions of Logia about the Lord (SBL, 2012), that what Luke had available to him in composing his Gospel was not only the Gospel of Mark (in agreement with Markan Priority), a version of Q (in agreement with the Two-Source Hypothesis), and Matthew (in agreement with the Farrer Hypothesis) but also Papias’ Expositions of the Sayings of the Lord. He refers to this as the Q+/Papias Hypothesis. Goodacre doesn’t find MacDonald’s idea convincing, emphasizing that Luke could have written his Gospel with little more than his knowledge of Mark and Matthew (and with the help of a little creativity).
Here’s the link to the well-moderated conversation.