Had this in the past, hardly worked with one drive in, didn't work with two in. Look for other options out there, besides the fact that this thing is outdated.
DoctorWhopperI had this and it was great. The USB2 is super slow, but it is not a bad way of copying drives, but it is painfully slow for SSD's. The other problem is over-heating if you transfer a lot of data to or from a spinning HDD. I could easily do 300 GB (and get really hot), but larger transfers more or less require a fan on the HDD.
This is a decent tool for making system images, but you should have eSATA. If one needs to use the USB2, then simply use your motherboard SATA connectors.