This is a completely reliable 4-way sushi rebalancer. It recovers gracefully from power failure and material shortages.
It uses a PLS rather than splitters or sorters to demultiplex and buffer the incoming materials. Consequently it is very small and UPS-friendly, and the integrated logistics upgrades may even help improve performance a bit.
On the sushi belts, two materials have frequency 1/3, and two materials have frequency 1/6. (Other distributions are possible, but require an additional splitter, and in my experience you usually want some materials on the belt with elevated frequency. One other possible variation is to turn it into a 3-way rebalancer and use only one splitter.)
Usage:
Set both PLSs to the same four materials, and set the outgoing belt filters such that the belts that join in a Y-junction have the same materials on it. The two outputs closest to the input belt are mixed with frequency 1/3, the other two outputs are mixed with frequency 1/6.
The PLS that receives the incoming sushi belt is used as a buffer. Set its four slots to "storage" and keep the capacity set to maximum.
The other PLS supplies additional materials as the sushi belt is depleted. Set its slots to "demand" and select the required capacity.