Many people have asked this question and while we don't have a specific answer we can give you some information. A lot of people ask this because they think that USB 2 cameras must be faster than USB 1.1 cameras. In theory that could be true but often times in practice you'll find out it's not the case.
Our USB 1.1 based cameras download pixels at approximately 400,000 pixels per second. If you ask the other manufacturers how fast their cameras are you'll find many USB 2 based cameras that are slower than that. So it's not just USB 1.1 vs USB 2 that's important but the actual download rate. Also, remember that in Astronomy you tend to take long exposures, typically 20 minutes to an hour so what do you really care if after an hour you image downloads in 20 seconds? Where you like fast download rates is in focus mode where our software use binning or partial frames to speed up the image throughput.
Finally, we have implemented USB 2 on our ST-402ME camera and with our design we achieved download rates of 1,100,000 pixels per second. While we plan on upgrading our other cameras to USB 2 at some point in the future no specific time table has been set.