The attached tutorial is the result author's attempts, several times over several years, to get started with XMega devices. It is part feature over-view - in other words, what are the "special" features that set the XMega series apart from the more common Mega/Tiny devices. It goes on, in this part, to describe what is different about the A, B, C, D, and E series and the primary features of each sub-series (A1, and so forth). I found this very useful in helping to focus which series I needed to spend more time learning about.
It is also partly a reminder (to the author) and others who are just getting started, what some of the conceptual "gotchas" are. These latter things were ideas that I struggled with the first time around and now recognize on this restart as needing some different thinking.
At 11 pages, it seems a bit big to just post as a message so it appears as an attached document. Feedback IS welcome! So are corrections!
Hope it is useful to folks out there.