This review of a book on the piano by the pianist and teacher Charles Rosen is so long, it must be a good substitute for the book itself. However, the review is interesting if lengthy. It throws a sop to Rod where Rosen says the pianos of the late 18th C. had more variety of tone than the modern ones do; elsewhere the pianist is critical of the authentic movement.
http://www.nybooks.com/articles/16678
http://www.nybooks.com/articles/16678