I agree.. only that there are many walled gardens
My reason for questioning your workflow has nothing to do with the walled gardens in fact. It was pointing to your converting on Calibre. Which means, that you in fact do not rely on any of the walled garden approach, but create your own library.
If you have your own library, it does not matter what your "reader" device is, because you have to convert to it's format and transfer there anyway. This is why I said the example is bad: because there is no significant difference between the various device's walled gardens. Your library is independent.
I used to have an "other" eInk device, which hardware wise had some things to ask for, but the software, although still in need of polish, was better than Kindle's for a number of reasons: It did support dozen of different formats, so no need to convert and in some cases damage the ebook formatting, and best of all it let me load my entire library of 20,000+ ebooks on the device. The Kindle sort of has troubles with navigating that many files and I have to make choice to load only few.
Unfortunately, I lost my other ereader and decided to try Kindle. While the Kindle has one major benefit: they provide software for almost any platform, and the hardware is great for what it is, their software might behave better, especially on the eInk Kindle device..
Anyway, to repeat myself one more time: Your example, which is about easy of uploading ebooks from Calibre to the different platforms, is not very appropriate, as it is Kindle software centric. (and the faults are Kindle software related, not platform specific)
