The wheel is constantly being improved.
Don Casey is the person we know. How many people visit these forums asking these questions who do not posses his book? Also, Don Casey does not provide much framework in the way of monetary costs associated with the used sailboats. I aim to give a more personal and tailored approach to the common sailboat buyer who is concerned about his bottom line.
That being said, Don Casey knows much more than I and more detailed information should always be sought from experts. This is merely a tool of convenience.