The iPod does a great job of sensing any changes you make through iTunes in adding/deleting songs and then synching accordingly. However, I am interested to know about this scenario.... Say I have "Dancing Machine" by the Jackson Five on my iPod. Then I find an extended edition of "Dancing Machine" that I want to put on my iPod. I delete the old and replace with new. Now here is the situation... Though I replaced the older version with a newer extended version the song title has not changed. That being the case, when I sync the iPod, does it know that I replaced a song with the same title with a longer version? Hope that makes sense.