I am not sure whether we have tested our FX3 device functionality with the system specifications that you have mentioned in your post. I will check internally and update you.
I have some updates on this post....
The desktop pc works pretty fine, had just trouble with the cable connection so it was just connected through USB2.0 HS. That works now fine for us with a desktop pc when connected to USB3.0 SS. But why is it so slow through USB2.0 HS? It seems that the transfers take really long time compared to USB3.0.
At the notebook I have still trouble. It works now better by deactivating the c-states in the bios of the notebook, but sometimes it is still really slow. Wired is, that after a reboot of windows 8 it has a different behaviour by booting FX3.