You are totally correct. The UNS path is not available at this moment.
We have a lot of improvements coming this year and The Mapped drives could be one of them.
If we release mapped drives support we will have to make sure we can support different permissions levels as well. If the mapped drives are on a Windows OS then you can backup those as logical drives from that OS.
Maybe you can check one more time ITbrain Backup at the end of the year. I am sure a lot of things will change and features will be added.