I just got done reading Helios Unbound
While I don’t agree with everything that is said in it, I did feel the author did a nice job in trying to put a pagan face on Golden Dawn rituals, with some historical records to back some of it up. I can’t speak to the effectiveness of the methods yet, but some of those Deities I work with have suggested I go through the 7 month process.
I will say that although there are a significant number of references of both historical and Occult books, I, personally, don’t know how much of the work is the author’s gnosis or historical “record”. He does sometimes state when it is his, but only someone with knowledge of the other works would know which is which in a lot of cases.
I DO suggest reading it. For $20, you get ~400 pages of material. I plan on starting (my version of) it soon, with few modifications. It seems to usable for anyone that has experience with ritual work, but not necessarily any in Ceremonial Magick.