The IT Review of the Hitachi - Deskstar T7K250 SATA II hard drive states: "The [250GB, SATA 1] 7K250 uses three platters, which is around 80GB per platter, but the [250GB, SATA 2] T7K250 reviewed here stands out because it is a twin-platter model, so each platter stores 125GB of data. The amount of data on each platter is significant because the tighter you pack it in, the less distance the read/write head has to move, and that increases hard drive performance."

I can see the argument but doesn't packing the data in more tightly also mean the drive might prove less reliable?