I rate the Elmdene ones for G3, you can wire them in a way so the magnetic interference shows as a separate masked signal.
Had a few sites mainly engineering units where tampers would happen, most often in the day, tried most of the available G3 RSC's and found this was the best solution.
Obviously G3 contacts have stricter mounting criteria (orientation, distance, alignment) over G2 but they are all designed to be mounted to a metal shutter directly as per the instructions.