The main downsides of this new approach are:
- It no longer reliably compresses a belt (48 steel furnaces with yellow output inserter, where the last 6 inserters are inserting on red underground belt constantly fail to compress the belt).
- It prevents undergrounds to be used for priority output, where it'll always prefer to get output from one machine, rather than another.
New behavior: https://youtu.be/08IH_2oeKms
Log for 0.16 attached, but don't really think that's useful.