I tried to write the guides from the point of view of a competent
programmer trying to get particular tasks done, while also giving enough
background that they can make intelligent decisions and understand the
context in which they are making them.

All of the guides have a focus on portable Scheme, explaining how to do
things that work across implementations, not just in one of them. In
aspects that are not portable, I put in tables and lists to compare
implementations so their differences and similarities are clear. The
guides could be taken even further in this direction.