Excellent thread in general!!!. ( this discussion, NOT the screws discussed )
BA fasteners have probably the best thread engagement possible with perhaps 90%.
Most modern metric screws are very easily stripped, EVEN those bought from suppliers like Farnell and RS. Both of which have Australian stores.
I cut my teeth on BA screws and have collected a small supply ( about 5 kilos in a beer brew tin
), and only use them for my own equipment. Slots cut into slotted screws are perfectly parallel and fit any decent screwdriver perfectly. Perhaps its another thing the POHM's got right.
Joe