Personally, I wouldn't increase Amazon's control over my data and would download electronic material outside of Amazon's control, hence my suggestions up-thread about how to find out where one's data is.
Here's what @paulraphael said in another thread about Joule:
"The simple fact that the unit won't work unless paired to an account should be cause to boycott it. This means, fundamentally, that you bought it but you don't own it. Buying something like this is a declaration of absolute trust, not just in the company's leadership, but in all future leaders, regardless of what happens economically or who acquires them. This argument is laid out pretty well by Wired, in reference to Microsoft's recent eBook atrocities: https://www.wired.com/story/microsoft-ebook-apocalypse-drm/"
There's no reason to believe that Amazon (like Microsoft) won't someday develop a new business model which includes shutting down their ebook presence. Of course, I'm also unwilling to have an Alexa, since I have difficulty being high-minded about Amazon's ability to restrain itself in data mining.
YMMV.
