One whole week? That'll depend on the event. Some events will end up with severe management issues, while others will benefit from the extra time because there'll be more time for submissions.
I think activity-based events might suffer from it, while submission-based events might benefit from it.
Anyway... For my events (Pokédex 3DSnap and anime captions), we would end up with a significant benefit due to the way stuff is run in these events. As for others, though... we need people talking about this.