I have both books and feel it is worth having both. One thing to also remember is that these authors spend a huge amount of time and in many cases spend huge sums of their own money to publish these books for not large returns. We as orchid growers need to support these efforts by purchasing these books to continue to support the dissemination of good information.
as for the culture chapter in Guidos book..... I am may be a bit biased on the quality of the culture chapter in Guido’s book..... but I did write the chapter as a hobbyist grower for the grower. Guido’s information on the native habitat combined with the culture chapter provides a great combination to tell the grower what these plants need to grow and thrive. I have told many people that there is no such thing as a hard plant to grow. If a plant was hard to grow, it would not exist in the wild. What may be difficult to provide is the ideal conditions that a particular plant needs to thrive, but the plant itself it not hard to grow. That is why it is important to understand the cultural needs of individual species as well as your own growing conditions. Hybrids then offer sometimes a challenge when parents require different culture, so a bit of trial and error may be required to be successful.
so in summary, buy both books and take the information offered by both to make yourself a better grower..... And support those making the investment to disseminate information!