John Mace is an ex-scientologist. Google 'john mace scientology' and a lot of stuff comes up. He was even in the book 'a piece of clear blue sky' an excellent expose of L.R. Hubbard. The whole identities thing is the same as scientology's 'valances'.
He is what is labeled by the Church of Scientology as a 'squirrel' - someone who takes Hubbards 'tech' and creates their own program very similar to it. I'd be a little weary of him. One of the things with identities/valances is that supposedly you get one every time something even slightly bad happens - stub your toe, your boss says something bad to you etc. You can often spend the rest of your life (and a lot of money) clearing these identities.
