Just an idea I'd like to throw out. Currently an item is locked to you the moment you put it on. What if instead, it was locked the moment you did anything that could increase its heat? e.g. entering a gate, or collecting a dividend. These actions would carry a warning/confirmation dialog.
Pro: You can try on that armour you just bought, decide you completely hate the look, and still trade it with a friend before you actually use it.
Con: May be a little more confusing than the nicely straightforward current system.