As I understand it, using one Kinect gives you 2m x 2m - presumably due to the range. Therefore, having 2 kinects where the second is 180 degrees from the first, 4m away, couldnt that double the range to an action area of 2m x 4m? Everything i've read says 2 kinects with ipisoft doesnt affect the action area (it stays 2m x 2m), but that doesnt make a lot of sense if you could arrange them like i've said.

Using a second Kinect is primarily intended for improved accuracy, not range. For that purpose, the capture areas of individual Kinects should overlap for an actor to be visible simultaneously from two viewpoints. Another reason for overlapping is that otherwise they cannot be calibrated using the current method (with slim rectangular object).
For the same reason we do not support more than 2 Kinects. You can find some discussion on this subject here:
http://forum.ipisoft.com/viewtopic.php?f=2&t=6245