According to the bench marking done in http://www.anandtech.com/show/4523/usb-30-flash-drive-roundup/8
a. pluging a usb3 flash drive into a usb2 host does achieve performance improvement (over usb2 flash drive)
b. but plugging a usb2 flash drive into a usb3 host doesn't achieve any performance improvement (over usb2 host).
Why is that ?
I would have expected both host and device need to be usb3 (superspeed) to see any improvement in read/write performance?