I think your operating temperature delta p tests are good, but I always wonder about at start up temperatures (0,30,50,70, whatever). On really cold days it takes awhile for oil to get up to operating temperature. The oil is thicker. How does that thicker oil affect delta p. This is the thing I wonder about on Subaru filters. Is the OEM or Wix 27 psi bypass needed to prevent bypass vs a 9-15 psi bypass on most filters at temperatures less than operating temperatures? Everyone says bypass events are limited events. I believe that at operating temperatures, but at cooler temperatures, I have no idea. There doesn't seem to any information on this, that I have seen.
I also think oil makes so many trips through the filter, that if the bypass was open half of all operating time, it would still filter the oil just fine.