Some of your points are well taken.
Dust is an issue and most filters are not designed with that capacity. However, the AMSOIL SDF Oil Filter
has a higher capacity than most filters. And yet is one of the highest flowing filters in its group on this independent test: http://www.oilfilterstudy.com/
"In the high-priced group, the Amsoil, Mobil 1, Fram XG, and K&N appear to be good choices."
"This filter appears to have very good filtration media and very good flow."
"It is the best flowing filter in the group of 50 µm average largest pore size filters."
Yet, even with this higher capacity, AMSOIL only rates their filters for 12,500 miles or six months of use. Thus if you really were going to use the full 25k miles, you'd need two AMSOIL SDF filters (but more of others).
Here are a few guys who ran both AMSOIL SAE 5w30 and Mobil 1 5w30 for a full year in an LS1 engine. While both oils showed excellent results, the AMSOIL had an edge in wear metals. There is some debate as to whether the Mobil 1 was handicapped by engine breakin by going first so they are redoing the Mobil 1 test. As an FYI, both these oils went significantly beyond 10,000 miles without problem.
I'd also like to point out that there is a difference between API certified and meeting API standards. AMSOIL far exceeds API standards:
AMSOIL 10w30 Excels in API Sequence IIIF Test
But you are correct in pointing out that only the XL-7500 line has gone through the API certification process.
As a counter point, I would like to point out that Mobil 1 just came out with a 15k mile oil that is not API certified and cost the same as AMSOILs 25k oil at retail. (AMSOIL Preferred Customers can get the 25k AMSOIL SAE 5w30 for about 20% less.) If AMSOIL is so far off the mark, how come Mobil 1 is following their lead?
Redline, the other leading manufacturer of high performance synthetic motor oil isn't API certified either. Redline recommends 12,000-18,000 mile oil change intervals with a filter change at 7,500 to 10,000 miles.