Since someone bumped this thread, I'll throw in my comments.
I read Secret History a few months ago and was enthralled. It was so refreshing and exciting to read a book by someone who maintained objectivity and skepticism about this subject, while unfailingly demonstrating a deep abiding appreciation and passion for the subject matter.
A rare thing, in the 'EU,' as it were.
I was left with just one big question: what is the nature of the dialogue in the partially-restored Biggs-in-the-hangar scene, which refers to 'father Skywalker' in a way inconsistent with 'father Vader'? Secret History mentions it in passing, without ever quoting the dialogue. If it is really inconsistent, I think that may be the strongest single piece of evidence for the book's central thesis.
[Of course, I can't help inserting on tiny nit-pick. There are some serious, systemic 'who'/'whom' issues, overlooked by the editor! I would love to take a crack at editing the 2013 edition! I think the organization could be cleared of some topical redundancies as well. But don't get me wrong--I loved in and devoured it very quickly!]