I have Audirvana and after picking up the Mojopoly tried the 2-week Roon trial (before having to pay). Audirvana works with Mojo (via USB) whereas Roon works with Mojo via USB or Mojopoly via network connection. Roon also has built-in DSP like cross-feed and the Audeze presets, whereas you need to use third party DSP plug-ins with Audirvana.
Audirvana and Roon did sound bit different to my ears - even when comparing both via USB to Mojo only. When I was comparing them sometimes I felt that Audirvana was subjectively better, sometimes Roon. But I already own Audirvana and it was a once-off cost of 75 USD or something, versus the yearly subscription model for Roon - which is more expensive for only one year use than Audirvana is for perpetual use. There are firmware updates for Audirvana too, which are included in that cost.
So in the end I uninstalled Roon before the trial ended. In all honesty I don't really understand why it's gotten so big in the audiophile community. I mean it's a perfectly fine piece of software, but it's very expensive when that cost is just to play music in your own collection, with Qobuz or Tidal etc. subscriptions on top of that (if you were going to go the streaming route). I'm also not a fan of subscription software either.
I'm not fully decided yet, but I'm thinking I may sell the Poly and just use Mojo via USB with Audirvana - it's just so much easier than using Poly via an app on my phone. I experimented with using m3u playlists and controlling playback just with GoFigure, but now that I've added a whole bunch of albums as playlists to the microSD card, it takes ages for GoFigure to load up the "Music" screen, so that's become a bit of a dead end. Although microSD card playback on the Poly does seem to extract more details than Mojo alone, I also find myself feeling that I prefer Mojo alone for longer listening - somehow Poly adds more detail but misses something else, like it's a bit drier or more sterile.
Maybe I'm also influenced by the fact that it's currently summer in Shanghai (where I am) and man it's hot. I can't imagine using Mojopoly on the go, in a case - which traps more heat - in this weather, which limits it's portable use to winter-only. Throw in to the mix that I also now have my Fiio M11 Pro which sounds great and is easy to use either for portable or stationary listening and the Poly just feels like a bit of a hassle (long story, but the M11Pro was in another country and I didn't think I'd see it until the end of year with coronavirus travel difficulties, hence took a dive with Mojopoly).