Ronny if you're still around:
valuesAxes should be implemented like so:
options="{valueAxes:[{autoGridCount:false,gridCount:10}]}"
Value axes hold each graph in an array, one javascript object per chart. Happy to expand further if you hit any other speed bumps
Also great thinking with the two ma-serial charts stacked on top of one another. Definitely gives the effect you were going for.
Fox