The most "non frightening" way to do it would be with rare earth magnets as you arent locked into the locations, and dont need to make holes in the vest. BUT i felt they shifted too much if i do an action pose and they also stuck to each other when suiting down which was just annoying lol.
I currently use the bolt method. I used E6000 to attach bolts to the armor and marked of the proper locations on the vest, made holes and added brass grommets similar to the screen used. The screen used suit used a plastic type "bolt" I haven't been able to find a good match for them, but im pretty happy with the regular bolts.
People have also used velcro with varying degrees of success.