Evidence so far has not shown any improvements in the various size limits on S2.

Assuming you are talking about Sonos playlists that is. Obviously each music service has their own playlist size limits, and those are definitely the same on S1 and S2 as the services don’t care which version they are used by.

65,000 tracks is the hard limit, however, there is also a space limit. If your meta data (Artist names, Track names, Composer, etc.) is verbose, it is possible to hit the space limit before 65,000.  Long file names can be a problem too. I’ve seen some rippers that will throw verse text plus the usual meta data into the file name. While this may be handy for the human, you could save a lot of space by simply using file names 1.mp3 … 65000.mp3 or whatever.

I have not seen any definitive statement about library space limits of S1 vs S2.