I appreciated Doug Chaplin's reflections. I would like to respond to some of his concerns. So this is a list of what I don't think about non-canonical texts.
1. I don't think that a newly discovered text is a reliable testimony to the historical Jesus or the early church. But I also question the use of the canonical texts as a reliable testimony to the historical Jesus and the early church. All early Christian texts have one main concern - theology. They are interested in interpreting Jesus and providing the faithful with the faith. Even Luke. How much history we can extract from any of our texts is a difficult question and a project fraught with methodological problems.
2. I do not think that "lost" texts automatically were suppressed texts, although the Church Fathers provide us with plenty of names of texts that were lost and found, texts that were suppressed by them. The question of their value, of course, is a question based on where you stand. If the text is "yours" then it is valuable. If the text is not yours, then its value may be reduced, even negated through systematic suppression and book burning, something we hear plenty of in the ancient documents. If you are in a powerless position - excommunicated for instance - then your text and ideas are more likely to fall out of fashion and be considered less valuable by others than not.
3. I do not think that the orthodox were the only ones who exercised power. The process of normation was a process that included both sides, and the haggling and name-calling and viciousness went both ways (as for instance the Gospel of Judas and the Testimony of Truth show us). But in the end, only apostolic Christianity emerged on top, and in power. And it used that power to erase the other forms of Christianity (and eventually paganism too, and used its power to distance itself from Judaism and denigrate it).
4. I do not think that orthodoxy was monochrome. In fact, it had several expressions dependent on its geographical location. These forms of orthodoxy themselves competed with each other over time, and resulted in the splintering of Christianity into East and West, and so forth.
5. I do not think that the non-canonical materials tell us the "right" story while the canonical texts and later orthodox tradition got it "wrong." The search for the story needs to take all the voices into consideration, so that we can reconstruct a whole picture of the historical origins of Christianity. Erasing or ignoring some of the voices compromises the integrity of the historical search.
6. As for whether or not the non-canonical materials provide us with alternative ways to interpret Christ - this is a contemporary theological concern, not a historical one of mine. A person's desire to deny the possibility of alternative interpretations seems to me to reflect his or her desire to maintain the status quo of the Christian tradition today. This is an issue of self-preservation, not history. Do the non-canonical texts provide alternative interpretations of Christ? Certainly. But whether or not a person finds those meaningful today, is a theological question controlled as much by church leaders as it is by the flock.