Either with the original base mesh from maya or the low level mesh at level 1 from ZBrush, it doesn't matter, it still looks bad. UVs were created with UVLayout and are fine since the color map looks fine. I am using the smooth mesh preview in Maya but I have not used the approximation editor since that has frequently caused issues with my models.
Hmm. When u say in step 3 you exported the normal map from z and used the original mesh, do you mean you didnt export back the low level mesh from zbrush?
Also how did you create your uvs?
Applied any mesh smooth/approximation editor?