Hi Natalie and everyone,
Just my two cents on the various books:
The Designer's Manual was written before Introduction to Permaculture --
so I think there were some improvements in style as well as additions to
the book. I didn't realize this at first -- I thought Introduction was
just a boiled-down version of the Designer's Manual.
In other words, both are valuable, as much for the illustrations as the
text. I do think the Designer's Manual is important for a detailed
understanding of permaculture principles and the design process as
Mollison conceived it. Also, if you plan to do any international
development work or work in other climates, Mollison's work has a global
focus. I think even if you aren't planning to do so, having this broader
perspective is important.
The Edible Forest Gardens books are much more focused in terms of
content. The emphasis is on temperate climate forest garden design and
implementation, with a particular focus on Eastern North America
(though much is applicable elsewhere). If you're looking for lots of
info on natual building, rainwater catchment, intensive annual
gardening, animal systems, urban aquaculture, community LETs systems,
etc., you won't find it here. It's not really an apples to apples
comparison (more like apples to hardy kiwi).
However, Dave's books are much better written and organized than
Mollison's, and volume two's design process section is worth the price
of the set. In fact, you can easily apply this design process to the
other aspects of permaculture (assuming you know what they are). Also,
Dave and Eric Toensmeir's work on the tables at the end of the books is
incredible, an invaluable resource for forest gardening at any scale. In
short, their work is to forest gardening what I wish the Designer's
Manual was to permaculture as a whole.