Since making the initial posting, I have recently managed to acquire a copy of McGrew's book, fortunately for what is now a fairly reasonable price. It is certainly an original copy: it has an inscription, date and signature of McGrew on its title page. I have also gotten a better idea of why his book has become in such high demand and price.
* The book was privately published and only 1000 copies were struck.
* While other books on 19th century coin silver products tend to address items that have the initials or names of the manufacturers, makers or retailers, McGrew explicitly states he has focused on the objects stamped into the silver products--eagles, five-and six-point stars, busts, etc.
* I'm still getting the feel of how best to use the book, it seems clear that McGrew invested an enormous amount of time editing and collating actual photographs (most taken by him personally) of the many variations and permutations of pseudohallmarks**, maker's marks and even journeymen's marks. By tracing the discernible degradation of images produced by the dies used, he is even able to trace the probably history of the dies as they pass from founders of silversmithing firms through successive mergers and acquisitions.
* By collating the images and data on producers use of types of objects, number stamps struck into the products, etc., he is also able to provide a list of names and the probable geographical location in which the product was made.
**McGrew maintains that the term "hallmark" is completely inappropriate for American made silverware, since America had no guilds or government departments mandating specific and required imprints to indicate specific things. Which makes complete sense, since America rebelled against the British at least in part because of the undesired pressure of taxation and legislation "without representation." Interestingly, he also believes that the use of objects "borrowed" from British hallmarks--anchors, busts, lions en passant--was simply because they were popular, available, and in the right sequence allowed silversmiths and retailers to identify which silversmith made them so as to acquire those products for their customers.