I have been trying to get the USB 3.0 support working with a USB 3.0 external HDD. So far it is very unreliable.... after installing the required drivers in my Win 7 VM... I can plug my external USB drive in, direct it to Win 7.... I hear the USB plugged in sound immediately... but it takes about a minute or more for it to assign a drive letter and allow me to use it. Then when copying files off or onto the drive it will hang like its not working at all..... then the progress bar will jump to about 3/4... then hang again... usually I have had to cancel out from waiting and waiting. If I uncheck the "USB 3" support in Parallels... then everything works solid. I get about 60Mb/s Read and 45Mb/s write to my external drive. I haven't been able to perform the read/write tests with USB 3 support since it just hangs. Anyone else able to get the USB 3 support working? I have a 15" Retina Macbook Pro. Thanks!