What USB3 controller do you have? I know there are quite a few chips that do not really support the full bandwidth. Are you using a laptop? Do you have access to a desktop machine with a separate usb3 PCIE card. For high bandwidth applications these seem to be the only useable devices. There is a pretty good list of USB3 laptops that have full bandwidth controllers here http://forum.blackmagicdesign.com/viewtopic.php?f=4&t=4277&p=148443&hilit=usb+3#p148443
It is for blackmagic compatibility, but the requirement is pretty simple, just full bandwidth and high performance. So far for me USB3 has been a little unreliable, (well not really but there are a lot of crappy controllers out there, including ones integrated into many motherboards. At any rate USB 3 has some pretty debilitating limitations on cable length (in my mind this kills the idea of a PTZ as you can only be a few meters away from the port for high bandwidth uses like HD video, as you could probably just reach and move the camera anyway). Take a look at something like this http://www.ebay.com/itm/10x-Zoom-High-Speed-1080P-HD-SDI-PTZ-Dome-Camera-IR-60m-1-2-7-CMOS-Auto-Focus-/261447245257?pt=US_Security_Cameras&hash=item3cdf785dc9 It has a similar specs (possible the same sensor by the looks of it) and is HDSDI so easy cheap and long connections between camera and computer and SDi capture boxes are cheap.