If speed and size are your major concern, this Seagate Backup Plus 2TB Slim portable hard drive could be your best choice. The “size” refers the portability as well as the storage. CNet independent test result shows it has 118.8 MBps write speed and 125.35 MBps read speed. Both are about half of the Seagate Backup Plus Fast which equipped with 2 hard drives and configured as RAID0. We would not recommend using RAID0 for backup purpose. It doubles the failure possibilities, plus the recovery process is more complicated. Costco’s offer is $79.99 after $15 mfr’s instant rebate. The deal run thru 11/29/2015.