In using the sermon editor as a means of creating lessons rather than sermons, I've found the following to be the major drawbacks.
- the metadata for liturgical date etc. which I know is coming but am impatient for
- the ability to add footnotes (this is a biggie for me although I'm using a funky workaround)
- the ability to import personal images
- the ability to distinguish sermons/lectures/lessons (not critical but nice for clarity and retrieval)
- the ability (unless I've just not found it) to switch off the automatic slides and only create slides on demand
In short, I think most of the things required for Lessons are things already asked for in sermons. It would take very little repackaging to advertise it also as a tool for Sunday School/Faith Formation teachers.
Nice job.