I haven't bought a bonsai book in a couple of years, aside from the republished Lenz book--which is worth every penny. Unfortunately, the bonsai book market favors entry level, since that's basically where the mass audience and money are. Good, in-depth, advanced bonsai books are very rare.
... this indeed is the unfortunate part. Finding a good reference is hard if not next to impossible to find, often if we search for specifics it is often found outside the "bonsai world" so to speak, as in this example or this one.
My reference was largely built some time ago, and albeit not as extensive as yours, reasonably comprehensive. I say reasonably because many books in my collection I would not have today. A large portion of these books were referrals and many were not perused prior to acquisition. Many a volume that I had the opportunity to view prior to purchase, can still be found in bookstores
I keep hoping someone will take up the huge challenge of equaling Nick Lenz regional book for other parts of the country--like a SouthEast book that covers bald cypress, tupelo, live oak, etc. A Western version that covers species from there, and so on. Those publications would probably have an extremely small readership and would be losers financially though...
... and hence the pitfall of such a recommendation. One of the reason I do not own that particular book, is for the exact aforementioned reasons. I would have no use for it in my Neck of the woods.
As time went on and experience gained I found myself seeking (not unlike you) more and more comprehensive references, to include but not limited to: specie specific. Generally the references were good to very good, but at times they seem to leave us "flat" or perhaps our anticipation built such a crescendo that such anticipation exceeded our rightful expectations. In other words we expected more than what was delivered. Hence the reference to the author or the publisher, where at times great material is delivered but perhaps the content insufficient for a "book" and hence filler material is added e.g pots, wiring, how to re-pot a tree etc... as you stated this is the type of material best left in a beginners book.
Getting back to Bonsai School, after having purchased and read Basically Bonsai, and reviewing Craig's site, not to mention the titillation provided by Craig on his site with his new coming book "Bonsai School", I honestly thought it would be a step above the rest. It mirrors many great books out there. However I must concede it does have one thing that other references do not, and that is the numerous artist involved in the reference and thus varying view points.
Is it a beginner book? No. I would have to classify it as intermediate to advanced. So how does Deborah fit into this? Well considering were Grizzly's post was posted (begineer's section) I believe her book which is now available at Stone Lantern is probably the most comprehensive and descriptive reference on how to care and raise bonsai for the lack of a better word.
Following is a list of what I deemed was 5 books that are must have, the 6th is strong optional. This list was compiled in 2006 and one I still endorse in principle, call it a starter kit for the lack of a better word:
Bonsai It's Art, Science, History and Philosophy
by Deborah Koreshoff
Bonsai techniques Vol I
by John Yoshio Naka
Bonsai techniques Vol II
by John Yoshio Naka
Bonsai in your Home
by Paul Lesniewicz
Home Gardener's Problem Solver
by Ortho Books
Vision of My Soul
By Robert Steven
As we advance in this art form I think one needs to focus on what is going to meet our individuals needs, not dissimilar to what you mentioned wrt Nick's book. Because I believe we both agree that many volumes are sheer repetitions of what is already out there, some with new twist, some not, and these include works from great artists. It is probably preferable to build a reference out of articles from folks like Walter, Nick, Colin etc... than trying to find a comprehensive book on the subject (cost). There are numerous articles floating about, some highly technical both artistically and horticulturally. Unfortunately even in many books the depth of detail pales in comparison to some of these articles written by unpublished artists. (Disclaimer: many have written articles for magazines etc... but as of yet have not produced a book)
As mentioned in the other thread, I am looking forward to Robert's second book, I have been waiting for a long time. I just hope I haven't built a crescendo...