Since the fleece being used is 20 micron(?) that would be a very small hole and you theoretically could run a lot of flow through it but have to run a lot more fleece replacements.
I'm considering the largest one, supposedly 1500gph max flow, since the surface area is a lot bigger than the smaller one. IMO, BM should have two options for the micron size, the smaller and a larger one at like 100 or 150 micron.
TBH, filter socks are so much work... unless you get like 20 of them and do the cleaning of all of them all at once.