OP:
If we are asking about whether to use a separate streamer or not, I think the answer is in which DAC do you want, and how badly do you want it?
That is, the separates vs. integrated issue is really as much about being able to pick and chose each component separately. In my case I really liked the Mytek Brooklyn (original) and got a separate streamer which handled Roon. My next move, if I ever stop talking about it, is really going to be based not on technical theories but on the sound of the DAC. If I can find an affordable all-in-one streamer DAC then that will probably be the way I go. If I fall in love with a DAC that does nto have Roon built in then I’ll go that route instead.
Honestly though I may give it all up and just go with a single HT processor with built in streaming and leave this all behind, mostly based on how many cables and wires and devices I have to have working in order to listen to music or movies.
It will however be a very very long time before anyone convinces me I need a kilobuck streamer alone to upgrade my sound experience.