[robinstewart]

Thanks for the feedback, "jklymak" -- the purpose of the article was indeed to be tentatively prescriptive, in the hopes that customers like you would point out if we missed anything.

You have a great point that overlaying data series like this can be useful for searching for patterns in multiple data series (what the HCI academics might call "exploratory data analysis"). OmniGraphSketcher does hope to support that type of use, so we will surely keep it in mind. Perhaps the future interface for multiple graphs should be more like a light table, rather than just a "dual y-axes" configuration. That would provide a lot more flexibility for data analysis, and you could just snap the x-axes to an overlaid position in order to get the dual y-axes effect.