Menachem.  I disagree.  I can build a page with multiple models. One model provides context for a popup, and a second model is used to conditionally render material in that popup. 

Can you give us a little more detail about what you are trying to do here? 

Hi Rob,

I did some further testing and realized that this issue only occurs in a very specific situation.

It appears that it occurs only when both models share the same sObject and the (model) field value of the rendering condition is changed after the popup is rendered, in which case the new (changed) value of the field has no effect on the rendering of the component.