What do you think about trying to combine both Kinect and PS Eye (Or webcam) cameras? Or using more than 2 kinects for better quality, and extended tracking zone?

We plan to start using RGB data from Kinects to get more accurate head and feet rotations.
Combining depth sensors with RGB cameras is a way complex due to different tracking algorithms used, and difference in hardware (lenses, frame rate). Besides, it may be not very practical because of different operation range. To cover the capture area of PS Eyes with Kinects one should place them inside. And also, adding a couple of Kinects to a bunch of PS Eyes will lead to bandwidth problems during recording.
Regarding increasing the number of Kinects, see this post:
http://forum.ipisoft.com/viewtopic.php?f=2&t=6245#p11940

Well, i'll stick with this thread i think.

Interference problems can be solved by attaching a vibrator motors to kinects ==>http://www.precisionmicrodrives.com/tech-blog/2012/08/28/using-vibration-motors-with-microsoft-kinect

So there is definetly only benefits from alowing users to use more kinects. You can really expand capture area by placing kinects on a larger area. dont forget about quality loss dependant on distance from sensor. So, onve you have more kinects, you have more data.

Using kinects and cameras is also possible, though I'm not arguing that it is a different approach, than the one you use ==> http://www.youtube.com/watch?v=T9Mg7qIZr1I

Yes, we know about vibration. But this is an ad-hoc solution, there is no off-the-shelf items for doing this. Do you suppose that all users should have necessary technical skills to assemble such motor themselves, or that we should sell our own hardware solution?

When placing multiple Kinects in such a way that their individual capture areas do not interfere, the more complex calibration technique is required to compute their accurate positions. Another problem is connecting many Kinects to a PC: each device must reside on a separate USB controller. In case there are not enough controllers, or a PC just cannot handle large amount of data being recorded, two PCs should be used for recording, and recordings should be synchronized afterwards.

Summing up. I don't assert that what you are proposing is not possible. Just pointed out that it's not so simple as it might seem at first look. And there is a plenty of other useful features that we want to provide to our users. Though we have plans to make research on using more than 2 Kinects in the next year.

Nevertheless, thank you for interest in improving our technology.

I'm not asking to make it quick, sure, first things first, but in the future that could be very usefull