Personally, I really prefer the cw vs flowrate (GPH or GPH). How this flowrate is achieved, is up to the user to put together.
The problem of course is that the headloss/pressure drop across the rad is mostly unknown (for common heatercores at least), except for what you've posted, which unfortunately doesn't include the latest BI products. If those were available, then, and only then would the above graph be usefull, IMO.
My .02
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