A little bit delayed news. It was born on 10th of december 2013. See here.
It has a clear brownish tint, but I am not sure if one could say that it is significantly more prominent than in non-selected plains zebras. What is interesting is that the stripes seem to fuse to a dark brown colour on the upper arms in this individual; I have noticed that in several other Rau zebras as well.
I think I'm going to draw another prediction of how Rau zebras might look like by 2025, additionally to my first one.