@rudy49 Let's try and help you out in your decision...
Tidal and Spotify are both supported by the ZS with the "connect" option, which simply means when you open either app and click on the little icon (usually a speaker) you will see the iFi Streamer option as a device to have your music come out of and into your dac! It's really for the most part that simple for those two options, because you will still be using the same app/interface you are used too for Tidal/Spotify.
"One app to rule them all" Yes and No...
Tidal and any drive you connect to the Zen certainly will be useable with Roon, you will just have to get used to the Roon interface, it's much like every other app with album covers, and a menu on the left to navigate, along with playback controls. However Roon will not incorporate Spotify, for that again you will have to use the spotify app for right now.
"HD files", by this I assume you mean Flac files CD rips of the sort that you already have, If i'm incorrect let me know. Connecting a hard drive is very simple in both Roon and with The included ifi.local App interface (iFi has said they have a dedicated app coming). So playback for you can either be done with it integrated into Roon, or thru the ifi app. Again it's just a matter of how you would like to do it.
I have never used M connect so I can't comment on that, but I think it may only complicate things further for you, again I could be wrong.
As far as the reconfigs and resets talk on here, I honestly take it with a grain of salt, We are all picky-ooni audiophile gurus here that wanna have everything perfect from the get go, and even if it is, we will undoubtedly whine when the machine we are here to type about doesn't do that one file format, or bit-rate, on top of acting like..."what do you mean it doesn't do that??" doesn't everyone need that, and if they think they don't, well I'm here to correct them!!! LMAO
I'm sure I just butt-hurt someone, but let it go I'm joking, lol
All in all here is what I would suggest based on what you have said so far.
Then Zen Stream with the included app will do what you need it to do, without anything else. Just follow the setup, connect to your Dac and start learning.
Once you are comfortable with it, might be a day, might be a week?? Then download a free trial run of Roon and see what you think.
But by all means do not by one thing and think it will do everything, ever, no manufacturer is going to do that, at least not one that wants to stay in business very long, and my final point is, if said manufacturer did make that product... What would that cost?
I'm pretty sure it won't be 399!
Hope this helps!
Cheers!!