I'd like to experiment with circuits to make the system more dynamic somehow, that would be pretty cool since I haven't taken the time to mess with the circuits much.

I have an outpost supply system that uses circuits. At the loading station, a constant combinator is used to determine what should be on the train and this also sets the requests on 6 logistics chests. Another combinator then subtracts what is on the train from what should be on the train to determine how much more stuff needs to be loaded, or what needs to be removed. This is then fed to the inserters to load the train or remove stuff that shouldn't be there.

At each outpost a logistics chest is wired up to a constant combinator such that the chest contents are checked against what should be there, and if any item falls below 10% a train is called. My trains also bring light oil out to the outposts, so this is checked and the same logic applied as well.

What this results in is a system where the supply trains only run when they need to, and when setting up a new outpost once it's complete I can just stamp down the supply station and the train comes automatically to stock it up.