I can’t say if you’ll lose sound quality with Roon when played through the 891. But, I wonder if it matters as you could use the MIND2 app for serious listening and Roon for music discovery if you found there was a difference. Best of both worlds and an easy switch of inputs.
And you might find you like navigating w/ the MIND2 app just fine. I’ve used it - and it’s significantly better than the T+A Music Navigator that I routinely use with my equipment. And the remote that goes with the 891 is vastly better too.
In my experience, all gear has some element of compromise. There is no perfect component. Yes, you can optimize each but there are limits there.
I like the Simaudio gear and think it’s a good value at that price. While I can think of a couple of competing options I also like very much in that range ($25-$40k), the 891 is the best value, comes from a great company from our friends in Canada who’s been around a long time and supports their gear with strong warranties.
You should do what works for you, but I don’t think the software will be problematic for you. To repeat myself - if I were to do it again, that’s the unit I’d buy and I’d have saved myself lots of money, time and effort.