Will they hold a loaded magazine throughout daily activities? I don't doubt that some people have tried magnets for carry purposes, but my experience with magnets for IPSC (sticking to chairs, doors etc...) leads me to believe that a naked magnet on the belt would not be truly 'practical'.
If the magnet is inside a pouch carrier (so the front face of the magazine is covered) then it would not be a problem, but if you are talking about an exposed magnet on the outside of the pouch or naked on a belt it is clearly against the rules.
In any case as Bob said we'll have have to wait for the rule book to have clarification.
