Thank you for the link to the 2016 discussion about the various BDP models available at that time. In the distant past I thought I'd read something about a limit in the number of files, but I couldn't find anything, so I decided I'd imagined it. Apparently not. Therefore, knowing what I know now, I wouldn't have bought the BDP-pi (Jan 2018). If there's a limit on any of the BDP models or, for that matter, any streamers from any other manufacturers, then the limit of addressable files should be part of the published specifications.
TBH, I don't understand how there can be a difference in sound quality. The BDP -- any of them -- is a traffic cop that directs files to the DAC via the app. As long as it doesn't lose any bits, how can it affect the sound quality in any respect?