Roon and Streaming Services

If albums /tracks are on Qobuz or Tidal they will not transfer over. 

What seems to stick are artists, so you can sign up for both Qobuz and Tidal, and say, tell Roon to start Annie Lennox radio and it will use both.

There is also a place to tell Roon which service to prefer (Qobuz vs. Tidal), but I don't remember where that is.

There are services for transferring playlists. You are going to have to do it.

I think the peoples use this to do it

https://soundiiz.com/

When I switched from tidal to Qobuz, Qobuz provided a program called soundiiz and after running it, 99% of everything converted over. Some artists I have found don’t let Qobuz play certain tracks but they allowed today to play them.

When I activate Qobuz will Roon keep all of my albums, artists and tags etc intact?  In other words, are those items stored in the Roon memory rather than the Tidal memory?

Roon still keeps all of your saved albums, artists, and songs. They are not stored on Tidal.  Since they are stored on Roon using Tidal service, you can't play those songs because they are tied to Tidal (which you already canceled), but you still know that is your saved song you want to play with Qobuz. Then you can click on the artist, find that album / song and save with Qobuz service.

And if one were to have both services ( not sure why one would ) how does Roon determine which one to use for a given selection ?

I have both services, some albums are better with Tidal, some are better with Qobuz.  In addition, some albums are available only in either Qobuz or Tidal. When you pick an album / song to play, Roon automatically picks the best service provider (Tidal or Qobuz) to play. You can control which service provider to play by changing it.