I have added this to SharedBatch: The default color is passed if setDefaultColor was not invoked on SharedBatch itself. Otherwise the old behaviour is used - each shared batch can have another default color than the target. Please check that it works for you this way.
I did not set a default color on that Node that the Spheres are under, nor on the SharedNode that references the Node. I only set them on the Spheres themselves. I'm too new to jME to know exactly what constitutes a batch, but I would expect that the way I set it up would let the Spheres retain their colors.
I did notice that GeomBatch sets an explicit default color of white, and that seems to overrule my default colors, even though leaf-level information in the Spheres should overrule that branch-level information.
Also, how often do the javadocs on the website update? There's no SharedBatch in there yet.
With each new release. You can build up to date javadocs with the Ant task included in CVS.