I dont know if this is a good idea. I am just thinking of thia at a safety stand point. The obvious dangers are sliding with cleats up and spiking an opposing player in the leg. High school players are still amatures and still need coaching on the proper sliding techniques. Accidents do happen and this could cause some serious injury. My next safety concern is self imposed. Metal cleats do get more traction on all types of surfaces.  This can cause problems on players that are not used to wearing metal cleats on different surfaces. Metals cleats stick in the dirt/grass better than molded cleats. Quick change of directions can cause problems when a players plants and turns, thier body goes one direction and the cleat is still stuck in the dirt going the other direction, and this can ruin knees. I have seen it happen in the pros before. Also, more and more school are putting in turf fields, and that can cause even more injuries. Just my two cents.