Just purchased Calibre Companion and using now Moon+ Reader. The books transferred over great into Calibre Companion. I have even figured out the line spacing. Sure wish there was a manual for Moon+ Reader. Lot to learn. My biggest issue is with my own ePubs. Calibre and Aldiko handle them well. But Moon+ Reader seems to do two odd things:
1) My covers are isolated like normal books in that the text for the first chapters are right below the cover. In purchased ePubs, the covers are separate as in Aldiko.
2) Also, what is TextView. Everytime I open one of my ePubs, there is this circle with a plus sign in it. Touching that brings up a blank dark screen with no where to go.
Moon+ Reader does have more options and it is growing on me. Calibre Companion is impressive.