Just wanted to say thank you for making this mod; monitoring the circuit network through time series graphs has been on my wishlist for a long time. My ultimate wish would be something like the vanilla production statistics GUI, a central part of the interface but for customisable circuit value history (using the new 2.1 radar channels perhaps?). Something for me to ponder on.
I've not yet come to the radar channels, but I will think about your idea. Have you tried the gauge mode (red wire), which will also render a graph on the third tab ("Gauge"), showing the input values?