Would love to see a mid-ground between the Splitter and the Smart Splitter. This version allows you to designate one or two outputs as "overflow". Traffic will only flow to the overflow output if the other line(s) are filled. There is no intelligence to determine the type of item - it only cares that the designated line(s) are filled.
Use scenario: only route unneeded (overflowed) items to central mall, otherwise they are assured to be directed to production factory.
Overflow intelligence could be added to Smart and Programmable Splitters as well.