All good questions Ferret, I can't answer them.
But I'm a "visual" kind of person and right off I noticed two things about the Yamaha oil filter that differentiate it from the Mobil-1 filter. The biggest concern I have is that the pleated cellulose element inside the Yammi filter doesn't have end caps and the diameter of anti-drain back valve doesn't reach out to cover the outer tips of the filter element pleats. I'm sure there must be something that prevents the flow of oil from getting to the "clean side" of the element by simply going around the ends but I'm not seeing anything. Perhaps the ends of the pleats are sealed but at the by-pass valve end of the pleats are open so I would imagine oil can sneak around that end. The ends of the filter element inside the Mobil-1 filter have metal end caps that may or may not restrict some of that from happening (I haven't cut open a Mobil-1 filter yet).
Maybe the filter designer knows more about what is happening than the internet? In operation oil is pushed from the outside to the inside. Wouldn't this close the pleats under pressure?
Then consider the pleats are designed to operate under compressive pressure. What happens if a "water hammer" occurs when engine quits? What happens if a shockwave occurs when there is a sudden halt of oil flow? Seems to me the open end would allow clean oil to backflow with low restriction rather than force it through the filter dislodging previously trapped crud. This is exactly the condition the "anti-drainback valve" operates.
So what if the anti-drainback flap isn't the diameter of the filter element? I think that is a good thing: all it has to do is cover the intake holes around the perimeter of the filter base. Any larger than that is waste and restricts incoming flow.
My point is that while it is fun to cut filters open to see what is inside, it is almost impossible with visible inspection to judge the filter's ability to do its job. One can admire the ingenuity of engineers. "Why use endcaps if we do not need?" Etc. But could one make everything out of stainless steel? The can, endcaps, endplate, wire mesh to contain the filter media? Would all this expense make a better filter of oil?
As I have long said about motor oil: all that matters is how it performs. "Synthetic" is not a performance specification although synthetic processes can produces a superior motor oil, just so long as the designer knows what is expected of a superior motor oil. Same applies to oil filters. Only thing that matters is test results. Tests we mere mortals can not conduct at home or on the internet.
Have thought about the difficulty in testing an oil filter. How does one create particles of known size for the filter to trap? And then how does one measure quantity of the particles after the test? My best guess is to use iron filings which could be collected using a magnet. But still no idea how to create known sizes. Or to measure the size of filings which were not trapped in filter.
Reminds me of a brilliant air filter test conducted by a group of Japanese street racers. K&N marketing would have one believe there is no better filter and no lower air restriction than with their oiled gauze product. These street racers took the airbox from a popular car and attached to a shop vac with a coffee filter inline. And a manometer to measure vacuum. The manometer gave a relative indication of filter restriction. Then they fed carefully measured quantities of copier toner to the intake. The coffee filter provided a visual indication of how much toner got past the air filter under test. No hard numbers but excellent comparison.
IIRC they found the oiled foam filter and OE paper were very close in ability to trap copier toner. The oiled gauze filters were very poor at filtering but were low restriction. But the oiled foam filter was also low in restriction.
My takeaway: foam filters are great for dirtbikes where high maintenance is acceptable. Foam filters should never go more than a year before washing and oiling. In my experience they don't go 3 years before the foam starts to come apart. On the other hand paper filters last decades without deteriorating. Excellent reliable choice. If a reduction in restriction is desired then just make the filter bigger. For example I suggest considering air filters on Porsche 928 and Ford 6.4L Powerstroke. The 928 uses a large conventional pleated air filter. The Powerstroke filter is amazing for how much filter area it gets into a small volume.