Programmable Inserters

[Telarin]

Programmable Inserters would be the next level up from Smart Inserters. They would be very similar, but would have some key differences:

Instead of all conditions applying to all items in the filters, each filtered item could have its own conditions.
Example: Move wires when wires on the red network is less than 100 AND move circuits when advanced circuits on the green network is less than 5

Additionally, Programmable Inserters would have a "direction" option for each item, so that one item could be moved "forward" (in the direction the inserter would normally work), while another item could move "backward" the inserter would move it in the direction opposite of its arrow.

[SilverWarior]

If my memory serves me corectly you can already use two paramerters for Smart inserters (green and red network).
But making inserter be able to move items into two direction is not posible with default inserters and as far as I know developers don't plan on including it.

There is an inserter mood that adds many new inserters. I personaly have never used it but I suggest you check it out. Maybe that mod has just what you need.

[Telarin]

Yes, you can set two parameters, but they apply to ALL filtered items, which means that in most cases it is not practical for a smart inserter to handle multiple items with parameters, as any parameters selected apply to all items in the filter, so you cannot have a smart inserter loading 100 iron AND 100 copper into a chest from a belt or other source. Yes, there are workarounds (requester chests, rows of multiple inserters, etc), but I think a higher end, more programmable inserter would be a more elegant solution to the problem, and would fit well with the general theme of Factorio.