Let me state at the outset, I am aware that some of this idea can be done using hoppers as item filters, but this idea is for something more powerful.
First, the crafting recipes: three hoppers, an item frame, and a block of either iron or gold.
The result would be a silver sorter, or gold sorter.
The appearance is a little bit like a hopper with an item frame on it, *but* there are three output chutes, instead of one, and instead of a big input hopper on top, the top is a blockish sphere (if that makes sense). One of these output chutes is the bottom, one is the left, the other is the right. Left and right are determined by whether the player is facing more north, south, east, or west, when he places the sorter.
Like a hopper, it is a container with some space inside. Unlike a hopper, it doesn't suck items in, they must be put in by the player, or by a hopper, a dropper, or a dispenser.
In the same manner as a hopper checks it's inventory, the sorter looks to see if it has anything inside it.
If there's nothing, it stops.
If it has anything in it's inventory, and the item frame is empty, one random item from its inventory is moved into the item frame.
If it has anything in it's inventory, and the item frame is *not* empty, it compares the minecraft id of the item in the item frame to
one item in it's inventory.
If the sorter is a silver sorter, then: if the id of the item matches that of the frame, it's dispensed out the bottom chute. If the id is *less than* that of the item in the frame, it goes out the left chute. If the id is *greater than* the id of the item in the frame, it goes out the right chute.
If the sorter is a gold sorter, then: if the id of the item does notmatch that of the frame, it's rejected and dropped onto the floor instead of being dispensed. If the id does match, other properties are compared, and it is dispensed out the bottom, left, or right, depending on whether those other properties are equal/lesser/greater than the same properties of the item in the item frame.
If you want to sort a bunch of different types of nonstackable items, a silver sorter can do the job. On the other hand, it will treat most types of stone blocks as being identical.
A gold sorter *can* distinguish between different types of stone, and between damaged vs undamaged tools, etc.
I'd be fine with Sorters only having one inventory slot, however if there were only two output chutes, and it could only accept or reject based on exact equality, then it would not be a sorter, just a better filter. I've nothing against someone implementing a block which filters items, but that would be a topic for another thread.
On the other hand, if you *truly* feel that sorters are too OP, there are a couple of easy ways to nerf them, without making them into mere filters.
First, if they required some hard to get crafting ingredient, in addition to everything else (e.g. emerald blocks, enchanted golden apples, end crystals, a nether star, dragons breath, totem of undying, etc), then only advanced players will be able to get one in survival or adventure mode.
Second, they might operated more slowly than hoppers. Presumably the server admins could choose how much slower it runs.
Third, if you feel a three-way sorter is OP no matter how it's crafted, and no matter how slow it is, make it a two-output device, with a default state of, "the bottom output chute is for items whose id is less than or equal to the item in the frame, and the rear output chute is for items whose id is greater than the item in the frame." Add a GUI to allow the player to switch between the default, and "bottom is greater than or equal to, and rear is less than." This would require two sorters to be used together, in order to be as powerful as a single three-output sorter. Or instead of a GUI, have it's behavior switch depending on whether redstone was powering it. Actually, this could be kinda fun, since if they're really expensive to craft, some clever redstoner might send items through a single sorter twice, once with the sorter unpowered, once with the sorter powered.
Fourth, make it only activate in response to specific, complicated to produce, redstone signals. Morse code, anyone?