For my case things are more complicated to bake normal map.
And importing in 3D Coat made artifacts i don't understand ??
Perhaps polygons inside the model due to the Merge on Subtool
i made ?
I'll go lot more fast by redoing entirely the model on 3D coat,
now i have the concept in 3D laugh

And Retopology under Zbrush is really far from all the options
and easy fast way you can do in 3D Coat !

For the workflow between 3D coat and Zbrush i'll have to do some tests to find the better !

Just do It !!

http://independentcreator.over-blog.com/pages/3D_Models-7792999.html