Blomberg, Criag L. "Chapter Seven: Tradition and Redaction in the Parables of the Gospel of Thomas." in Wenham, David (editor), The Jesus Tradition Outside the Gospels. Sheffield: JSOT Press, 1984, 177-205.
Blomberg considers the Gospel of Thomas to be of great interest because many of the statements attributed to Jesus are similar to statements in the Synoptic Gospels (Wenham [editor] 1984, 177). Eleven of the thirteen parables have New Testament parallels. Of particular interest is the view that Thomas may well not have used the Synoptics as a source, as suggested by the substantial differences in arrangement and style (Wenham [editor] 1984, 178). Blomberg reviews many of the arguments and, though many of them are plausible, they are not overwhelmingly compelling. He also notes that some arguments for dependence on the Synoptic Gospels are fairly strong (Wenham [editor] 1984, 181).
Counter to my expectation, Blomberg notes that narrative tends to grow shorter rather than longer over time. He sees this happening in the different Synoptic texts. The parables which appear in Thomas and which are parallelled in the Synoptics are, in fact, shorter versions. Blomberg walks through some of this evidence (Wenham [editor] 1984, 182).
Blomberg's evaluation of these parables does suggest to me that he is more hesitant to speak of heterodoxy and Gnosticism than I am. What he is able to accept and evaluate in friendly terms tends to provoke me to outright rejection on theological grounds. His conclusion, however, is related to his overal thesis. Thomas has numerous parables which combine tradition and redaction. Where there is redaction, Thomas typically brings in Gnostic ideas (Wenham [editor] 1984, 195). Due to the apparent redaction, Blomberg thinks it unlikely that we can identify any particular pre-Synoptic materials with relaibility (Wenham [editor] 1984, 196).