Here's a sample mine - I'm using a handmade balancer (it's just using a splitter on pairs of belts and then plugging each of them into one of the two 4->4 balancers, which I can make by hand), and then they get plugged into the loading areas. It does work in that all the stations get fed evenly, so I'm happy with it.
The display shows how much ore has been exhausted from the patch, and the text on top shows where it started. It also has circuitry to lower the priority if it's running low (the constant combinator outputs 50, and if the chests are below a train load the decider outputs -25), which helps have better mine utilization.
This is a pretty fresh mine, so the number is low. My most used patches have ~7m used, which should be about 14m ore with my current mining prod of 10. Science is still coming from my starter base for now (the only thing the megabase is used for right now, aside from feeding the starter base, is tier 3 modules).