I second, third and fourth the ability to select items and have the GUI filter to display where those items are. Even better if you can also filter for certain members. The new GUI looks great, this would just be the icing on the cake. The read whole belt contents feature is super neat. Filtered pum...

TL;DR Adding memory to trains which can be set and read by the circuit network, increasing automation and creating novel gameplay. What ? The memory can only be read/set when the train is at a station. Other than that, I'm not sure implementation details make much of a difference. Why ? Main reason...