12 bit monitoring is great when grading LOG for digital cinema (DCP) on a 12 bit digital cinema projector.
To have the correct black level and correct contrast ratio you will need the correct review room contrast ratio in the cinema: 1500:1, 100:1 intra frame. Movie theaters have 1200:1.
You will also need the correct white light level (14 fL) in the cinema to get the contrast correct.
You will also need a dark room.
See this post for more info on good projection.
Resolve 11 beta 2/Desktop Video 10.1.3 adds dual link 3GB HD-SDI DCI 12 bit monitoring with the Decklink 4K Extreme and the BlackMagic Design UltraStudio 4K
12-bit 4:4:4 video monitoring support with Decklink 4K Extreme and Ultrastudio 4K (up to Stereo 2K DCI)
-What’s new in Resolve 11 Beta 2
BlackMagic resolve website