I've been pondering this problem. It seems likely that Hype 4.0 will be released at some point. When that happens, I'll have to decide what to do...
- Create "A Book About Hype" as an ePub for iOS devices and Mac
- Create "A Book About Hype" as an app for multiple platforms
- Do neither, because books are hard to make.
If Hype goes multiplatform, the app version looks better. While an ePub is crossplatform, the interactive widgets from Hype are not.
So, if you're targeting iPad, using iBooks Author and ePub is an easy way to finish the project. If you're targeting additional platforms, a custom app for each platform will allow you to create better results.
Although, distributing an app is a lot harder than distributing an ePub... if you're avoiding places like the App Store or the iBooks store. The reason is that an ePub can be loaded instantly, while an app needs certificates. Also, unlike Android, an iOS app can't be easily copied to the device.
After battling with this issue for years, I like ePub projects more than apps. That's me though. The solution for you might be different, as there are many issues to consider.