The sorter would take any items from the container above it that match the items in the four slots to the right, and put it in the left most slot before it sends it to the container it's pointed at.
Not only would this take less space than the bulky redstone sorter, it would be able to sort out items that don't stack (such as records and filled buckets) and it would be able to sort out a total of four different items, which would allow you to have a simular items that don't stack in one chest, (without an even bulker sorter) or all your types of logs in one chest
As for the crafting recipe, I had a few ideas the, but most of them were bad and where a reference the components of a redstone sorter.
Though you can use/base the recipe off the first three I think this one is clean, makes sense and can be remembered. You could have it take a single diamond, but I think there should be a balanced cost for a item that takes less space and is more useful.
You could add even more use to the sorter by having it move stacks at a time, which would not only make a better sorter, but could be used in farms to collect and move items 64 times the speed of normal hoppers.