Redshift Real Time is currently in beta. At this time Redshift RT is most helpful for scenes primarily made up of hard surface models and shaders due to current limitations for things like subsurface and hair shading commonly found with more organic assets. 

At this time, due to the current limitations of Redshift Real Time, it is recommended that RS RT be used with new scenes as you are likely to find incompatibility with many shader networks found in pre-existing scenes. For example, the Maxon Noise shader is unsupported at this time so any shader network that makes use of one will result in a red shader that indicates incompatibility when rendered with RT.