I think there may be the case of apples and peauts.
1) Push-pins, magnetic or not, can be pushed into drywall. Standard stud locators can be used to do general finding; the pins for marking. Magnetic pins, unless long and pivoted like a compass, would be useless for finding. 2) Pins of any type, unless propelled at high velocity, will not punch thru iron or steel ("metal-based"). The magnetic base would act as a shield and nullify any possibility of finding the studs, even with X-ray backscatter.