i have 4 different external box USB3 connected to 2 different PC with pci-express card usb3.0 and usb 3.1.
i test speed for reinilialize disk (surface test desctructive).
When a disk is connected on a sata connector on the system board, speed for read, write and initialize surface are respectively +/- 80mb, 80mb, 46mb.
When this disk ins put into one of the USB3 external box, speed become respectivally 80mb/ 80mb/ 26mb.
In all the test i have done, i can perform the initialed surface test at 46mb in a external usb3 box where smartinfo was not available, when i upgrade the firmware of the box to get the smartinfo available then speed for init go down to 26mb/S.