Smart Objects should ignore their resolution and base their size on the current document with %s. If I have a (A) 5x5 document at 50 ppi, and nested within it is a (B)10x10 document at 100 dpi. At full size the (A) should be 2.5" or 100%, however, at 2.5" it would show as 50% of (B), and at 5" it would show at 100%. This can get very confusing, and cause issues of something being blown up to much larger a size than intended. Not to mention when you have smart objects that are nested within smart objects.