I think Onyx focused mainly on pfdreader to make good/acceptable pdf reader, recently.
It is not 100% for reading pdf, but it is fine. I do not know, how it works with epub... It is based on Adobe library, which causes many problems.
Booxtor should comment, but I think they might focus on epub soon as pdf part might be completed soon.
If you do not want to wait, return Firefly or if it is not possble sell it. And buy something different what suits your needs better.
