Mine started with about six small heads and now has probably 20 or more. In my limited experience, they seem to be bullit proof. The worse the conditions get, the more they seem to like it. I do have mine in fairly bright halide light and medium flow. The heads on the lower section that are shaded don't seem to do as well. They get as large as the others in the day, but get much smaller at night, and don't have as much tentacle extension. Still, they seem to be holding their own.
As for background music, I was thinking more Atom Heart Mother... Or maybe Echoes...