I'm more worried about program interface complexity than code complexity. I don't want a program that does everything under the sun; I want a simple Bible reader that does one thing (reading the bible) and does it well. Now, in some ways, adding support for commentaries makes sense. Possibly even note taking, though that has the possibility to really add complexity to the UI. But maps?
As far as support for different Bible formats, that can easily be done with different backends - the code is already structured in such a way that would make that relatively easy. If conversions and file formats are your specialty, I would really appreciate if you could do some work to see if we can read the Bible+ format. If you can get even basic code in place, I can tie it in to Katana.