Post #10 assumes common momentum transfer, not common separation speed, and shows that jumping separately is never better, regardless of mass ratio. So the answer to the OPs question (which of the two tactics is better?) does NOT depend on the mass ratio.This is discussed in posts #10 and #13 and the answer depends on the mass ratio. Common separation speed is about the only one that can be realized with actual legs and bodies.
Post #13 contains no complete derivation, just an assertion:
Are you talking about a non-zero, non-infinite ratio here? If yes then what is that ratio?There must be a M:m ratio where the two strategies give the same resultant velocity.