The people who develop the mcmmo plugin are quite smart... im sure they already have ideas on how they will handle the new minecraft update. They will make sure each thing gives its own special benefit or ability. On the server side yah just gotta observe and see how things go and make changes based on what you see. Currently the mcmmo plugin has quite effective benefits for unarmed/swords/axes/bows however we just use axes and bows mainly.