Many magic items which one might wish to use at the same time use the same magic item slot. For example, a high-level cleric faces a tough choice between an amulet of natural armor, a periapt of wisdom, and an amulet of health. Is this a deliberate balancing factor, that is, characters are supposed to be forced to chose between natural armor, Wisdom bonuses, and Constitution bonuses, or is it something that can be changed with minimal balance implications?