dustfaq outdated? Filter factor for pleated cannisters?

Hi all,
I'm getting close to buying a DC system that will be for a fixed ducting arrangement in my home/hobby shop.
I'm leaning heavily towards the Penn State DC2000BCF - has the 1um pleated cannister filter up top (83 sq.ft. surface area), plastic bag below.
In calculating my SP requirements, the dust FAQ (yes, I see it's dated May 2000) at http://mypeoplepc.com/members/dstig/dustfaq_2.html
mentions the filter factor. Says a 30 micron bag counts 1" SP, BUT for a 5 micron bag you should deduct 30% from the final working CFM, and a 1 micron bag cuts the effective CFM in half!?!? ... Can that be right? Or is that assuming a 1 micron BAG - with its limited surface area - as opposed to a pleated cannister?
I spoke w/ Bill at PSI, and asked him what the equiv. SP-inches is for the exact cannister for the DC2000. He had to check and call me back, and did, and said to allow/factor one-HALF inch SP for the filter factor.
That's a helluva lot different (better) than a 50% cut in effective CFM.
I see in the FAQ that the author seems to address this in the "Better Filter Bags" section; and he makes special note of the Onieda Cyclone w/ pleated filter, "unlike any system currently available."
Can someone help clarify this for me?
Thanks, Chris
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