Hello Dominic,
It looks like a feature rich system. It has support of multiple devices on the bus, local variable plotting, ADC data plotting etc.
The common thing I can see with SimPlot is that both can plot data. I am trying to keep SimPlot, well simple and easy to use.
It would help the Arduino users if you mention how the tool is useful and what are its use cases. I mean explain features other than plotting analog data. It might not be evident to many people from reading the initial post.
Cheers and good luck.