The best use I've come up with is inserting fuel into trains.
I've always found it annoying to run power to inserters for refueling trains. My trains are powered with nuclear fuel, not sure how long one fuel powers a burner inserter but it's an extremely long time.

Also as others have said, on ...

This

The one thing that is probably going to keep me trying to pursue this is the fact that, when a train is waiting on the main line, if ANY train leaves the stacker, the train waiting will re-path and pick one of the open spots. I'm not sure what is causing this. I'll will test around and see if I can ...

UPDATE:

I figured it out. I set up a clock to repeatedly count to 200 and put a rail signal just past the entrance.
When the count is < 1, disable the entrance signal.
This flickers the chain signal and when a train is in the block that reads the chain signal, the repath happens.
I was reading ...