Ceramic replacement filter in whole-house unit

Where else to get advice on cleaning water, eh?
We're on a well, ~230' deep. We've got iron and who knows what else. The house came to us with GE SmartWater softener and at some point before we bought, a tiny, hardly-worth-it, filter was installed in line to filter the house.

Not being in a position to invest in a proper $1000+ system, I sprung for a GE GXWH35F, which, if nothing else, allowed a much better flow rate to things like the shower. Our water's OK and we use a RO system for drinking.

It's now coming up to the time to change out the filter and I belatedly discover the Doulton ceramic filters (think: DE!) and there's a replacement for this unit (SMF100J-5).

Flow rate's a big deal for us but I can't find any data on that. Anyone have any thoughts on this? I suspect with better filtration we'll sacrifice flow. And I invite any other comments on whole-house systems as well.

Thanks
C.