Anyone who says paid software is guaranteed to be better is either selling you something or delusional.

FOSS has almost never disappointed me as an end user. Windows disappoints me every time I use it.

I have an older touchscreen, non-backlit e-ink Nook, and I don’t use any of the Web interfacing or store to buy books. I do all my library management and acquisition on desktop and then USB transfer it. Mine freezes and stutters occasionally, mostly when browsing menus or waking up from standby mode, so it’s not perfect. But it’s acceptable and I’ve done plenty of reading on it. Mostly it was cheap. I think I paid less than $40 for mine used. My last Kindle was a Kindle 3G and it behaved pretty much the same after I jailbroke it to read epub format.

Personally I just abandoned my Kindle library when I bought a Nook. That’s not particularly helpful, of course, but it’s what I did as part of kicking Amazon out of my life entirely. I started buying my books from non-DRM sources.

I will say this: you may have paid for “licenses” for those books, but you don’t actually own them. Amazon can rip away your access to them at any time. Were it me, I’d simply pirate DRM-free copies of the same books. Though if you can successfully strip off the DRM and convert them to open-source formats, that’s just as good and carries less risk. Every time I’ve converted ebook formats with Calibre it’s done weird stuff to the text: letters incorrectly interpreted, missing punctuation, page breaks in odd places, and enough of them to be annoying. Something to consider. Maybe that kind of thing can be corrected but I haven’t yet figured out how.

Overly complex? That’s a baffling thing to say about any operating system when they are all insanely complicated. Windows and MacOS and a typical desktop Linux distro contain more code than a single human could write in a lifetime.