The EMC link would be much more flexible if you could add some filters on what items to allow to be inputted into the block.

The ability to lock the input slot to accept only those items specified in the output slot
The ability to not accept items with NBT and/or Meta Data

These two options would allow it's use more widely connected to storage networks or other applications where a large assortment of items are coming into it that would otherwise be difficult to filter.

I could add a button that would only make it accept items that its also outputting, adding more slots, especially filter would be overcomplicating the block

For what it's worth, just about every mod that offers any sort of item transportation(Thermal Expansion, Ender I/O, etc.) has filters built into them already..