The problem with the current system is that it somewhat clashes with consumption multiplier feeding. If you have to supply 10 of 3 different yields, the currently automated unit is very inefficient. I have been thinking of setting fully automated units to use a DoaNE like system. The max capacity is reduced, but at the same time it can make fully automated transports more efficient since we expect them to have lots of frequent transports of a low amount of yields of each type. If the player takes over, the GUI could be reduced to just dumping the entire content in the city and the vanilla slot system is restored. Not ideal, but it would be far easier to code than a full blown system where humans can use it too.