I'd put Book as CG, myself. If only because in War Stories he was more than willing to do a little violence for no more reason than to help Mal. Also, the fact that having switched sides and/or slipped down that slope, his actual orientation is always slightly in doubt. Particularly when you think of that episode where River is hearing everyone's internal thoughts (was that Objects in Space?) and Book is quite "I don't give a rat's ass...etc.) Sounds like he can be mighty unlawful to achieve his ends.

I guess I still wish we'd gotten more of Book's backstory. He always came across as the most complex character to me, even more so than River.