Well???!!. you ignited the BS KK KL thing again, just look at the posts below, not your fault. I use 2 FZ 55L + 1 FZ 27L + fermentausirs. The FZ units work very well so long as you are not completely stupid like others who have posted pictures of exploding collection jars because they closed the butterfly vave and left them attached (fermentation not complete, pressure build up, explosion iminet) . Idiots. A Fermzilla would be one of the better choices to replace a Coopers barrel but READ the instructions.
Yeah i know, should leave pissing matches well enough alone, although it is fun to kick the hornets nest every once in a while.
I don't plan on pressure fermenting yet but it would be something i will consider further down the line, a FZ or FK seem pretty decent doesn't matter what flavour kool-aid people drink they are amazingly similar.