I too have a digital only main system (I have a record player in my second system mainly as a historical conversation piece ), and I agree with what you say, Roon has many positive attributes, and sounds very good on the Extrene.
However, after I first heard TAS I literally never used Roon again on the Extreme, the sound quality trumped any UI drawbacks & lack of discoverability for me. I joined the XDMS alpha program and was even happier with that. Then around the turn of the year a back end update was released for XDMS which took things to a whole new level of engagement, with the tantalising prospect of even more to come, especially in conjunction with the switch & router. Although XDMS is not going to replace Roon features like multi room, I’d say you are in for a very big and very pleasant sound quality surprise when you try it!
I still use Roon btw, I really value the discoverability, I just don’t run it on the Extreme through my main system any more.