That is interesting. I'm not sure I find it comforting, though.
This thread suggests in part that the Wix air filter may be built for longevity, but consequently passes lots more total particulate.
The (admittedly-now-aged) M+H pamphlet on fleece media talks specifically about much-improved longevity (vs size).
Should we be perhaps especially-interested in a test of 'fleece' air filters, in order to see whether increased filter longevity in a fleece-type filter leads to far more particulates passing through them, as was the case with the Wix tested here?