The cartridges I was quoting were the Hayward SwimClear and the Pentair Clean & Clear plus. You can see the curves here:

http://www.hayward-pool.com/pdf/manu...xx25-C7000.pdf
http://www.pentairpool.com/pdfs/CleanandClearOM.pdf

But this cartridge has even lower head loss:
http://www.pentairpool.com/pdfs/cleanclearrpOM.pdf

But you are right, there are some lines that are worse. I would never recommend those since they are usually pretty small.

As for cleaning a cartridge, I would never use a pressure washer. I use a small nozzle on the end of the hose which doesn't damage the fabric. That is probably one of the reasons why my cartridges have lasted so long (> 8 years).