most efficient way to supply ammonia to lowside recirculator

[RANGER1]

Not sure if this has been asked before, but see following description.

2 stage ammonia refrigeration plant
-40 C low side with liquid recirculator pumps
-10C intercooler/recirculator with liquid pumps

Several ways to maintain -40C liquid level
1/ high pressure liquid from receiver subcooled by separate internal coil in -10 C then feeds -40 C
2/ low pressure liquid transfer from -10C to -40C
3/-10 C liquid pump feeding -40C
4/ other methods don't know or can't think of on 2 stage plant

2 & 3 the same efficiency
What would efficiency difference be between 1 compared to 2 or 3, much?