What are people's expectations here? Personally I think it's silly to vote for anything less than 2TB with the cost per GB so low on these drives. I'm praying for the day they create a 3TB mobile drive, but it has yet to come.
Just a heads up: WD passport drives have the usb plug soldered directly to the controller board of the hard drive. If the drive should ever fail, data recovery centers will charge you extra since they will have to solder SATA wires to the controller board in order to gain any access to the drive. I avoid these drives whenever possible, just because losing access to the data on a backup drive isn't ideal :P