IMHO loads in /empties out can be a blessing since you don't need to return empty coal drags to staging or return loads to the mine between op sessions.
Yes indeed. And in broader terms, I've never been a big fan of deadend staging for exactly this reason. But, ok, I get it, for an operational-intense layout, that can be the price to include a desired real or fictional interchange connection.
Speaking of the blessings of loads/empties, another is the flexibility to engage in whatever level of activity you feel like at the moment. You can actively switch the cars (making sure that certain hoppers are positioned to receive the required grade/size of coal) or do minimal switching by dropping the loads and picking up the empties, or just use two opposing trains as the OP has suggested.
No matter how you mix up these options, all the cars end up in the right place waiting for the next session, just as Brakie noted.