I wonder why transfer rates vary a lot between different drives. I can understand that USB 2 and USB 3 will influence transfer rates or transfers between internal and external drives will vary. What baffles me though is that sometimes the rate for the same type of operation (e.g. imaging) using the same PC and external drive on the same USB port with the same software program is quite different. What other factors play a roll here. If I do an image, a transfer rate of 44 mb/s is pathetic.