Yes, I found it very useful. Warning, the following text contains many SPOILERS!
For example for fuel. I like that when you have multiple furnaces and don't know how to distribute wood and coal between them, you can simple throw all wood and coal into one InputMerger and from there distribute to all furnaces. If you want to add coal to an EssencePurifier, you could loop the InputMerger, because if the Merger would be 'stuck' at wood for a while, waiting to distribute it, a looped Merger automatically continuously shuffles itself so it reaches coal much quicker.
You also can set the output of EssencePurifiers to a looped InputMerger, and from there anywhere you need: fire for the advanced furnaces (I forgot the name and can't loop it up as I just finished the game), vitriol for the Transmuter or essence for upgrades. Once the output of the InputMerger hits something that can't be used (i. e. something full or essence), it would stop distributing elements, but if you loop it to itself, it shuffles itself and quickly will reach something usable in its output again. This way when you want to change an EssencePurifier, you only have to change its inputs as its output is automatically distributed.
Also if you want to make a lot of the last thing of a Transmuter (was it quicksilver? I don't remember), you could loop a Transmuter to itself, but eventually it will stop because it can't feed quicksilver to itself, but if you connect it to a looped InputMerger (which itself is connected to the input of the Transmuter), this will filter the quicksilver but continue to feed the Transmuter stuff it can process.