Not much information, just what I've been told by D-Link and users experiences.
One thing to consider as well, performance on the USB port is not the greatest. Yes it works well however in regards to large size drives, the router would need to catalog everything on this large drive and should it become full, it would take a long time for the router to complete any sort of cataloging if you make changes or add files. I personally would not recommend using a large size drive in this case. If you need something like a large size drive to be shared, I recommend sharing the USB drive out on the online dedicated PC, use a NAS device instead or use a USB to network adapter.