Hi. I have only just joined and have also recently made the switch to Affinity Designer (from earlier versions of Adobe Illustrator / Photoshop).
I love the fact that I can get good results intuitively and fast in AD compared, even without a lot of hours under my belt.
Nevertheless, the prospect of a dedicated book or a series of tutorials sounds very appealing, particularly if the focus is on Character / Mascot Design, creating vector landscapes, backgrounds etc.. In this way, not only will we master the tools but also gain valuable skills that can be put to use immediately on real projects.