I agree with jmacon. It is the hardware that matters, specifically the chip sets that are used in the devices are crucial: in the computer, in hubs and in peripheral devices like cameras, focusing controllers, mounts, etc. The problem with the USB bus is that there are specifications and the manufacturers of devices don’t pay attention to them. The bottom line is: there are combinations of devices that do not cooperate well.
I am using the following devices:
Notebook: Fujitsu Lifebook E 746 (Windows 7 Professional SP1)
4-port powered USB3 hub: EXSYS EX-1183HMVS (chip set: Genesys GL3520)
Camera: ZWO ASI294MC Pro
Guiding camera: Starlight Xpress Lodestar X2
Focusing controller: Seletek Armadillo2
USB2 -> serial converter: Digitus DA-70156 (chip set: FTDI / FT232RL)
Mount: Takahshi EM-400 Temma 2M
The notebook is connected via 5 m USB3 cable to the powered USB3 hub. The camera is connected to the USB3 hub via 3 m USB3 cable. The guiding camera is connected via 0.8 m USB2 cable to the USB2 hub of the ZWO ASI294. Focusing controller and USB2 -> serial converter are connected to the USB3 hub via 3 m USB2 cable. The mount is connected to the USB2 -> serial converter. I use USB3 cables from Delock. The USB2 cables are from different suppliers.
Under no circumstances I experienced a stuck data transfer on image download.
Bernd