Right now I am working on an SBL paper on Mark 1:1, "The Son of God Was in the Beginning" (perhaps you can guess from the title which reading I am arguing for). In any case I am working through the patristic citations, which has been very rewarding. One very important father who cite Mark 1:1 is Origen.
He invariably cites the short version in several passages in his Commentary on the Gospel of John, in one passage in his Commentary on Ephesians (fragmentarily preserved) and in Contra Celsum. Gordon Fee who has examined Origen’s Marcan text cited in the commentary on John describes it as “Egyptian” (Alexandrian) in Books 1–10 (1, 2, 6 and 10 are extant). As already Griesbach observed, Origen seems to have used a different copy of Mark for the latter part of the commentary, and B. H. Streeter subsequently found this text to be especially close codex Θ and its relatives (incidentally, Θ also has the short version of Mark 1:1). Origen completed the commentary after he had moved from Alexandria to Caesarea (ca. 231), and, hence, the text-type was labeled “Caesearean.”
However, the three citations of Mark 1:1 are found in the former part of the commentary where Origen used the earlier copy of Mark before he changed in Caesarea at some point. Contra Celsum, on the other hand, was written in Caesarea (ca. 248), whereas it is impossible to say when and where Origen wrote his Commentary on Ephesians. In sum, Origen’s citations of Mark 1:1 appear in works written in distinct places covering a long period of time; it is of course impossible to assign this particular citation to any specific text-type. Besides, the issue of text-types in general has been debated, and the existence of a "Caesarean" text-type in particular has been questioned. Is it a distinct text-type, and, if so, only in Mark?
This post has been inspired by an odd dream I had tonight, which I only remember fragmentarily. I dreamt I was going on a bus travel to Caesarea with other text-critics to somehow find out the truth about the Caesarean text. I remember entering the bus and taking my seat beside Ulrich Schmid when suddenly I realized that I had forgotten to bring my luggage! I had to climb off the bus and I missed the trip. I wonder if the other guys found the Caesarean text.