I applied the firmware fix at for the USB3-SATA docking station http://plugable.com/2011/02/08/firmwa… and it seemed to improve the situation at the time.
However, now I have started a big copy job with a fresh drive and the disconnect problems have returned. They seem slightly milder than before and since I am using RoboCopy it can eventually reconnect to the drive and continue, but so far it has dropped off the bus 3 times during the course of just copying 80G so far. I’m using the Renesas USB 3 controller I mention in the comment thread for the firmware update. The drives are all 2TB WD Green drives, WD20EARS.