Hi Mark!
you never did so already
you are in for a surprise, me thinks
(I've done those tests, IMHO and in my experience more dust is more visible when closing down aperture, I always test w/50F1.4 @F4/F8/F13, and 'clean' at F4 mostly means 'still dirty' at F8 in *my* book)
And as you said, best way to find out is do the tests yourself the next cleaning-time.
...*my* €0.02 worth...
My kindest regards,
Max@Home