Presumably the maglock is connected to an access control system rather than a fire alarm system. The green break glass fail safe should break both poles to the magnet, close to the magnet itself. This will eliminate the potential for earth faults causing the lock to fail to release. However whilst you can get double pole green release buttons for use inside often these are connected to the access control system panel rather than directly breaking both poles of the magnet itself. There are many considerations, its up to your risk assessment......Mag locks are generally more durable than electromechanical locks provided they are properly secured to the frame, the usual problem is self tappers being pulled out as opposed to moving parts problems and wear associated with electronic keeps, some of which fail unlocked others fail locked..... if theres a stay put policy are persons awaiting at the door at risk from fire assuming only the occupants of the flat involved will evacuate and the staircase will be a relatively safe area....