Just a few thoughts from someone who uses Spotify for virtually all my music listening.
I accept that the quality is sub-optimal, should Spotify ever release a 'full flac' version at a sensible cost I would get it, but for the moment I am reasonably content.
With my speakers set up in optimal position, I think I can hear slight improvements in terms of soundstage, instrument decay and possibly detail resolution when moving from Spotify to Tidal but the differences had to be listened for. With the speakers in their normal, everyday position these differences are not really noticeable.
What is very obvious though is the difference in quality between different recordings and even different versions of the same recording, even on Spotify, these differences are far more important than any difference in bit rate. Trolling through some old Stones songs recently, the difference in quality between original album recordings and the Hot Rocks compilation albums was obvious.
From time to time I find these differences in quality to be quite annoying, at some point I have to try a better streamer, maybe a Linn or a Unitiqute to see what happens, could be interesting.
Edit... Using Spotify Connect seems to be an advantage in several respects, no gapless issues for example and the ability to control the music from virtually any wi-fi device in our fruit based household. Wouldn't like to lose that.