A feature that proved to be very useful was being able to click and input/output and see the flow of nodes through the shader.
The images attached are from TRIs Infernal Engine which was initially modeled around UDK.
You can see how if you click on the Diff input, it highlights the path of nodes that feed into it in red.
When you click an input/output in the middle of the shader it shows you where the nodes go in Green and shows the nodes that feed into it in red.
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