Can you name that study, I'll get it and then we talk again after my vacation.
As for the wear particles and the factory dirt....
Some manufactured engines can be quite dirty even for more then one oil change.
If you have a good airfilter, the oilfilter is not that important as one might think. I've seen an engine running in Saudi Arabia. It was running fine, even though the oilpan was filled with about 10 mm with fine dust particles in oil. The oilfilter was OK, but it was not capable of collecting this fine dirt. You could see that the piston and bearings where a little pre-damaged.
However, to use a good oilfilter as "back-up solution" can not be a mistake. Just in case...