[Steve_Haley]

There is a lot to be said for the old unix model, i.e. apps as individual modules rather than one program trying to do everything.

I think you're betraying your background with that statement about Unix Unfortunately a lot of people these days like the one-stop-shop approach; they want an app that just solves everything for them. A lot of people would prefer CC to have a reader app built-in, for no other reason than just not having to find another app on Google Play. It doesn't seem like a big deal, but the demo version of CC has many bad reviews from people complaining about this.

Many calibre users that I know, including myself, indeed keep hundreds or thousands of ebooks in the library.

Duplicating books only happens if you actually tap the "Read" button in CC on iOS. Until you tap the read button, the book exists only in CC's folders. If storage space is a concern, you can also delete the book from the reader app once you've finished reading it.

Can CC accept an EPUB file sent by another app running on the same iOS device?

Unfortunately not directly. As chaley wrote, we need to have a connection with calibre when importing books to match them up with calibre's own library. However, we might be able to have a feature where it can accept books while you're connected as a wireless device. I'm picturing it working similarly to the existing "Scan when connecting" feature, but I haven't looked into the technicalities of whether this would work.

I personally feel a reader app that can sync positions between ios and android and works with calibre companion will sell well. [... list of other features...]

While syncing across iOS and Android would be a great feature, the issue is that it's a niche feature on an already niche app. Not many people have an iPhone and an Android tablet, or vice versa.

However, if truly none of the syncing works well on the Android readers already, that could be worth investigating.

The downside here is that the reader app would need to be subscription based, not purchase based.

True; we'd probably have to rent server storage ourselves to be sure that it was reliable. Luckily for my 'day job' I write that kind of thing all the time. Like the rest of these features, none of this is terribly difficult; it's just a bit time consuming. I'll add it to the suggestion list for after we finish the iOS version.

Library size of 1 - 20 being 31% of CC's users.

Is that including the demo version? If not, I really didn't think that many of our users had such tiny libraries.