Barramundi ( BRM )

[SPC]

I think you are trying to fit a square peg in a round hole. The listed pie funds and unlisted unit funds invest in approximately the same underlying stocks but they operate in different ways to meet different needs. They do this to suit investor preferences. The unit funds don't suit me and others for reasons of liquidity and pricing opportunity.
Nothing to do with big fish vs small fish although I do note that barramundi and marlin are both fish and they look like tasty ones to me.