Tracking dom-repeat created child nodes, updates in addition to adds/removes

Question

I have a host component that should track information in its child nodes. Child nodes are created using a dom-repeat:

<!--host-->
<dom-repeat items="[[data]]">
  <div>...</div>
<dom-repeat>

I can track the nodes being added or removed by dom-repeat:

//host
attached: function(){
  this_observer = Polymer.dom(this).observeNodes(this._nodesChanged);
}
_nodesChanged: function(info){
  // handle info.addedNodes, info.removedNodes
}

But dom-repeat recycles existing nodes when its items changes. So, for example, when data changes from [a,b] to [c,d] it will reuse the two existing nodes and therefore _nodesChanged won't be called.

What is a good way for the host component to know when recycled child nodes have been updated? The host component should be able to do so without knowing the inner workings of the child components (encapsulation principle).