The new "Persuasion" book test is without a doubt the best of Black's efforts in that genre to date (and, as a researcher and collector of forcing books and book tests I have all of the ones they have produced or marketed). While several of their book tests, including the two you mentioned ("Man Who Knew Too Much" and "Dracula") are specially modified versions of genuine books and will withstand at least a cursory examination without the "secret" being detected, "Persuasion," along with Josh Zandman's 2006 "A Christmas Carol" which Blacks also offers, uses a totally different (albeit not original with Blacks) methodology.
Although the origins of basic method employed in "Christmas Carol" and "Persuasion" can be traced back to the 1940s and has been used in various forms in any number of book tests since then, the innovative adaptations employed in "Christmas Carol" and "Persuasion" represent milestones in book test evolution and make these two of the very few gimmicked book test books that can actually be read from cover to cover with virtually no likelihood that anything at all unusual will be detected. In fact, the nuances incorporated in "Persuasion" represent a subtle but significant improvement over even "Christmas Carol."
I use multiple methods and as many as ten different books -- no more than four or five of which are gimmicked -- and all of which will withstand the closest scrutiny -- in the book test routine which is featured prominently in my own performances. Of the hundreds of gimmicked books in my book test collection, "Christmas Carol" or "Persuasion" are two of only six or seven that I would even consider using in my show. I have been using "Christmas Carol" regularly since its release and I will now be alternating it with "Persuasion."
Other than giving both "Persuasion" -- and "Christmas Carol" -- my unqualified endorsement and assurance that their cost is more than justified, I am reluctant to reveal further details here.
If you feel that you need more information, you may send a private message to me at firstname.lastname@example.org