I also saw a presentation about Inkling some time ago. Its an impressive concept with great visualizations. Its limited because you can't self produce content and its limited to iPad access.
The Moodle course is naturally controlled by your college. You can add your own content or commercial contents. You can add live communication via chat or messenger.
With Inkling you don't know who is answering to your questions. I wouldn't expect that a lot of communication will be in your book if you just read a chapter.
I see more opportunities in LTI standard (integrated in Moodle 2.2. as external tool). You can integrate external applications into your course. If you use a Moodle system as LTI provider you can interconnect the same forum into different systems and communicate with students in different Moodle system and it looks like a forum in your course.
Thanks for the advice to ePub 3