Yup, up to 3 if they don't exceed 7TB in total. I have an older unpowered hub, with a Amazon enclosure running a 5200 RPM 6TB survailace drive (not sure if any of those make a difference) and a 2TB MyBook and I've posted the pictures of the screens that show that I get the 6TB and 2TB to show up at the same time.
Voodoo, I don't know, but I get 8TB with only 2 EHD's (and the order they are plugged into the hub does matter). But the official dish line is 7TB in total.