Noted amended article and results(unless my memory is failing)
New PSID of 0.15(0.105mH2O) at 0.96gpm compared to an eyeballed 0.28(0.2mH2O) in Billa tests:
http://thermal-management-testing.com/slitedge.htm
However PSID a 0.46(0.3244mH2O) at 0.9gpm for the PolarFLO* corresponds to an eyeballed 0.28(0.2mH2O) in Billa's tests**
The picture gets fuzzier as the results come in.
*
http://www.overclockers.com/articles879/
** :
http://www.thermal-management-testing.com/polarflo.htm