Quote - pardon me for interrupting such a spirited discussion but, it seems to me that in order to get both cameras oriented correctly both cameras would have to rotate on the same center axis...

Yes, it is necessary that the two cameras rotate around the same point. However for the purpose of producing a stereoscopic image, it is not necessary (though it may be desirable) that the axis of rotation be half way between the cameras. The axis can be anywhere, and the image will still be stereoscopic.

In my 'StereoCamsNoToe_v01a' the axis is directly in front of Camera_A, and thus offset slightly to the side of Camera_B. This may not be ideal from the point of view of manipulating the cameras or making calculations, but it's the simplest way to go, and does not compromise stereoscopic nature of the images.