Barefeats has published benchmarks of transfer speeds between a Mac Pro and the USB 3.0 AV Drive from CalDigit.
One of the newest products is the USB 3.0 AV Drive from CalDigit. "Wait a minute. Apple hardware and software does not support USB 3.0." Yes but CalDigit has developed OS X drivers for their PCIe and ExpressCard USB 3.0 host adapters. We tested their PCie adapter and their USB 3.0 AV Drive on the 2010 Mac Pro. The transfer speeds for this single 7K HDD USB 3.0 enclosure is impressive. Also impressive is the write speed of the FireWire 800 port on the same unit. (Order from CalDigit or PowerMax)