I have just completed the first book with RC2. It works (???)
Neither 64bit version will run on Win 7.
The 32bit version runs OK. The manifest is out of sequence and if I change the name of a section in Book Browser, content.opf does not update.
You are very close. One thumb up.
I'm very anxious for the final version so that we can get down to arguing about ver 5.0.