I have pking with all 4 for awhile now, and I must say I agree with these statements. Not only do you hit slightly harder than in OSRS with all 4 worn, but using them is completely risk free. It's kind of baffling. I think the best route is to have the defender and the feros be broken upon death, anywhere in wildy. When broken, they cost 10m each to fix. The player who kills them should be rewarded with a cash stack of 8m (to add a slight sink). The infernal cape is fine the way it is. The (i) ring should be dropped as a regular ring as well. This forces edge pkers to think twice before wearing these items, knowing there is punishment for dying.
Great post and very detailed. Well done.