I have a small idea that i don't know if it would be good to add or not, but you should consider adding an area for the DM to do private rolls in a normal room without having to open multiple dice rooms.
Their is a code that you can use.
/self CODE - perform roll for yourself (not logged)
/self 1d20 is an example
Drop lowest / keep highest 5 of 6D10: #6D10H
Highest 4 of 6D10: #6D10H4
Lowest 4 of 6D10: #6D10L4
Middle 4 of 6D10: #6D10O (<- that's an O not a zero)
It still would be good to have ability to make secret rolls between player and DM without alerting others. Sending screenshots of using /self is too tedious. Besides, those can be easily faked. And opening eight dice rooms for a single game feels somehow wrong...
I kinda agree it would be nice to send secret rolls to other people, but I also think if you're the GM and you have to send _screenshots_ of /self results to players, you probably have more trust issues in your group than Rolz can address ;)