First of all, i am not sure if you can avoid this method? I only do QNAP-NAS and on those there has been a massive issue-storm with disappeared local storage mapping in Roon for something like a year now. One of the work arounds has actually been to use network mapping instead.
What does it mean then, if your storage is mapped using a UNC path?
Well, the network stack will be involved in the file transport path which in turn mean that Roon will consider this a network storage.
That means that “on demand change notification” will not be available as on SATA/USB storage. Rescanning will be done on scheduled intervals.
Unsure if audio analysis and identification will take a performance hit when we are talking the same machine. Playback performance will be similar, and i don’t think audio quality changes would be discernible.