the advantage of the Innos Zenith is that I would have it working as both a roon core/server AND as a streamer. This would mean being able to replace my Macmini and adding a streamer rather than having to upgrade the server as well and adding a streamer.
Given your specific situation this makes a helluva lotta sense, and I agree having the streamer and server in the same box is a relatively small compromise (if it even is a compromise, which I have my doubts all things considered) that comes with a big dose of convenience and simplicity. Seems like it very effectively solves all your issues in one box, and as mentioned their Sense app is highly regarded for both usability and sound quality and is continually being improved/upgraded even further, and to top it off their customer service is top notch if ever needed. Handwriting would seem to be on the wall here.