20 micron nominal is terrible. The Wix XP is 50% @20 microns, even their own regular cellulose based Wix/Napa gold is 95% @20 microns. If you call the Wix tech line they will tell you the regular Wix/Napa gold is their top tier filter which is why it has a much higher efficiency, they designed the XP for longer drain intervals.
Compared to the other microglass filters the Amsoil and Royal Purple is 98.7% @20 microns, the Fram Ultra is 99.5%+.
You can't compare oil filters much by cutting them open. You compare them based on their holding capacity and efficiency which most manufacturers hide.
Wix removed all the beta ratios from the filter specifications because of all the bad publicity they received here. The information can only be obtained by emailing or calling them. It's also found doing a Google search where we have covered this numerous times.
Personally I have bought the regular Wix/Napa gold filters before so I have no problem with Wix in general, but knowing what I do now i try to get higher efficiency filters for the same money.