I tried a thirty-day trial of Tidal, but Roon seems to be insisting it will not incorporate until I update the membership, i.e., have a paid membership. Ergo, I have had no experience with the Tidal-Roon connection.
That could as well be a Tidal requirement that Roon needs to follow.
I would suggest sub for 1 month to test out whether it makes much sense for you. I personally use Qobuz since I prefer to buy my music, and Qobuz has a sub tier which gives you a 50% discount on high res music download purchases. So, for me, the amount saved in my music purchases exceeds the cost of the subscription.