I am having the same problem with multiple usb 3.0 drives not transferring at the superspeed rate. I was about to return the drive today, but noticed other people are having the same problem. After plugging and replugging the drive in, swapping the cables and rebooting, it is now registering as Superspeed 3.0. There is no rhyme or reason as to why it is now working, but someone suggested that if the first device you plug into your MBP after rebooting is a USB 2.0 device, then both ports will only register as USB 2.0. I believe this may be true.