Once the base mesh is created, we just need to add details to it. You can check the accuracy with the reference model by smoothing the model from times to times as you go along.
This method is interesting in that we see where we're heading and what results we want. We just have to worry about the mesh itself. It is not the case with other methods such as box or edge modelling, as we build the mesh by successive approximations (box modelling) or blindly (edge modelling) and we need to worry about the polygons AND the volume at the same time.
When the mesh is finished we get a first version of the model.
Although close enough to the reference, we can enhance it by moving vertices to have a more subtle geometry.
In order to do that, since the Smooth modifier of Maya is not particularly fast even with iteration set to 1, I convert the model to Subdivision Surface.And as if by magic, we can move vertices with the equivalent of a Smooth with iterations set to 2, even with a 1GHz CPU!
Displaying subdivisions not being as efficient as polygons, I use an instanced copy of the object which I move to another OpenGL window (Panel/Tear Off) with the ZBrush model as a reference too. I can then move vertices and see in realtime the result on a clean view. Of course it's much better with two screens as all recent 3D graphic cards have dual screen functionalities and with an LCD as second screen, no more excuses! :)
Once we have finished, we can convert the Subdivision Surface back to polygons (Tessellation Method/Vertex).
Voilà! Reworking of the base mesh is over. We can now edit UVs and export the model to ZBrush again to add details for displace or bump maps. This test was a bit extreme if we consider the very basic low poly mesh or the final reworking of the base mesh which was very dense. But the aim of the test was to really try and reach the limits of this technique to see if we could go from one extreme to the other.
As a final word I would like to say this method allows to work on very complex models in a limited time, which could be disheartening with a more standard technique. The Zbrush phase is really a pleasure and reworking the base mesh is simple and quick.