Quote>If the cards were as reliable as you claim, why would Nikon go >to the trouble and expense of adding all of the hardware and >software required for secondary slots in their high-end >cameras?<Quote<<<
There are other benefits than just backup: 1. You can shoot overflow and extend your shooting without carrying or changing cards. 2. You can shoot RAW + JPEG like I do at weddings. 3. You can designate one slot for Still and the other for Video.